Liquid crystal display device

ABSTRACT

Provided is a liquid crystal display device capable of switching between a transparent state and a scattering state, reducing or preventing a decrease in transmittance in the transparent state, and reducing or preventing a decrease in luminance in the panel central portion in the scattering state. The liquid crystal display device includes, sequentially from its viewing surface side toward its back surface side: a first liquid crystal panel; a light source; and a second liquid crystal panel, the first liquid crystal panel including a polymer dispersed liquid crystal containing a polymer network and liquid crystal components, the light source being configured to irradiate a back surface side main surface of the first liquid crystal panel with light from an oblique direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2021-110811 filed on Jul. 2, 2021, thecontents of which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION Field of the Invention

The disclosure relates to liquid crystal display devices.

Description of Related Art

Liquid crystal display devices are display devices utilizing a liquidcrystal composition to display images. Typical display methods thereofinclude applying voltage to the liquid crystal composition sealedbetween paired substrates to change the alignment of liquid crystalmolecules in the liquid crystal composition based on the appliedvoltage, thus controlling the amount of light passing through the liquidcrystal display device. Such liquid crystal display devices are used ina variety of fields owing to their features including their thinprofile, light weight, and low power consumption.

Driving systems for liquid crystal display devices that display colorimages have been developed. One of the systems is a field-sequentialcolor (FSC) system. A common FSC system divides a display period of asingle screen (single frame period) into three subfields, andsequentially switching among red (R), green (G), and blue (B) lightemitting diodes (LEDs) which serve as a light source of backlightillumination. Synchronously with the switching, the system sequentiallyinputs image signals of the colors of the illumination rays from therespective LEDs to the liquid crystal panel to control the transmissionstate of the panel, thus enabling additive color mixing on the retinasof the viewer's eyes.

The FSC system enables color display without formation of subpixels in apixel, achieving a high resolution. Also, the FSC system directly useslight from LEDs. This eliminates the need for color filters with a highdegree of absorptivity in each pixel, and thus achieves a high degree ofuse efficiency of light from each LED.

See-through displays have drawn attention which are capable of providingdisplay where the background of its liquid crystal display device can beseen through the device. Liquid crystal display devices using a polymerdispersed liquid crystal (PDLC) have been developed as liquid crystaldisplay devices for see-through displays. A PDLC contains liquid crystalcomponents dispersed in a polymer network. Application of voltage to thePDLC changes the alignment of the liquid crystal components and producesa difference in refractive index between the liquid crystal componentsand the polymer network. The liquid crystal display devices use thisdifference to switch between a transparent state and a scattering state.

There are known techniques related to see-through displays based on theFSC system. For example, WO 2015/053023 discloses a liquid crystaldisplay device that includes two liquid crystal panels and is capable ofproviding color display without color filters by FSC driving of thelight sources. JP 2016-85452 A discloses a liquid crystal display devicethat causes light from an FSC-driven light source to be incident on alight modulation layer between paired transparent substrates.

BRIEF SUMMARY OF THE INVENTION

Since the liquid crystal display device disclosed in WO 2015/053023provides transparent display and color display using a polarizing platein combination with the FSC driving, the transmittance in thetransmission display is insufficient (for example, about 25%).

JP 2016-85452 A employs a system that guides light from the FSC-drivenlight source extending along a side of the liquid crystal panel to theinside of the light modulation layer (for example, polymer dispersedliquid crystal). This causes loss of light due to a factor such asdiffraction or scattering by the thin film transistors or the polymerdispersed liquid crystal inside the liquid crystal panel. As a result,light from the side of the liquid crystal panel is significantlyattenuated as it travels toward the central portion of the liquidcrystal panel. Thus, when the liquid crystal panel is increased in size,the luminance in the panel central portion may be insufficient. Thismeans that there is a restriction on the size of the liquid crystalpanel, and the size of the liquid crystal panel is difficult to increaseto a middle or large size.

In response to the above issues, an object of the present invention isto provide a liquid crystal display device capable of switching betweena transparent state and a scattering state, reducing or preventing adecrease in transmittance in the transparent state, and reducing orpreventing a decrease in luminance in the panel central portion in thescattering state.

(1) One embodiment of the present invention is directed to a liquidcrystal display device including, sequentially from its viewing surfaceside toward its back surface side: a first liquid crystal panel; a lightsource; and a second liquid crystal panel, the first liquid crystalpanel including a polymer dispersed liquid crystal containing a polymernetwork and liquid crystal components, the light source being configuredto irradiate a back surface side main surface of the first liquidcrystal panel with light from an oblique direction.

(2) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), the first liquid crystalpanel displays an image based on a field-sequential color system, andthe light source includes light-emitting elements configured to emitlight rays of colors different from one another.

(3) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1) or (2), and the first liquidcrystal panel further includes a thin film transistor.

(4) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), (2), or (3), and a distancebetween the first liquid crystal panel and the second liquid crystalpanel is a [cm] or shorter, where a is calculated from a length 2 a [cm]of a long side of the first liquid crystal panel.

(5) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), (2), (3), or (4), and theliquid crystal display device satisfies the following (formula 1-1):1 cm≤h11≤{a/(tan θ11)}  (formula 1-1)where a is calculated from a length 2 a [cm] of a long side of the firstliquid crystal panel, h11 [cm] is a distance between the first liquidcrystal panel and the light source, and θ11[° ] is an angle of incidenceof light from the light source on the back surface side main surface ofthe first liquid crystal panel.

(6) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), (2), (3), (4), or (5), thelight source is a first light source and disposed correspondingly to oneof a pair of edge portions of the first liquid crystal panel facing eachother, the liquid crystal display device further includes a second lightsource that is disposed between the first liquid crystal panel and thesecond liquid crystal panel and correspondingly to the other of the edgeportions, the second light source is configured to irradiate the backsurface side main surface of the first liquid crystal panel with lightfrom an oblique direction, and an angle of incidence of light from thefirst light source on the back surface side main surface of the firstliquid crystal panel is the same as an angle of incidence of light fromthe second light source on the back surface side main surface of thefirst liquid crystal panel.

(7) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), (2), (3), (4), (5), or (6),the liquid crystal display device further includes a back surface sidelight source between the light source and the second liquid crystalpanel, and the back surface side light source irradiates the backsurface side main surface of the first liquid crystal panel with lightfrom an oblique direction.

(8) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (7), and the liquid crystaldisplay device satisfies the following (formula 1-1) and (formula 2-1):1 cm≤h11≤{a/(tan θ11)}  (formula 1-1)θ11−θ21>10°  (formula 2-1)where a is calculated from a length 2 a [cm] of a long side of the firstliquid crystal panel, h11 [cm] is a distance between the first liquidcrystal panel and the light source, θ11[° ] is an angle of incidence oflight from the light source on the back surface side main surface of thefirst liquid crystal panel, and θ21[°] is an angle of incidence of lightfrom the back surface side light source on the back surface side mainsurface of the first liquid crystal panel.

(9) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (7) or (8), the back surface sidelight source is a first back surface side light source and disposedcorrespondingly to one of a pair of edge portions of the first liquidcrystal panel facing each other, the liquid crystal display devicefurther includes a second back surface side light source that isdisposed between the light source and the second liquid crystal paneland correspondingly to the other of the edge portions, the second backsurface side light source is configured to irradiate the back surfaceside main surface of the first liquid crystal panel with light from anoblique direction, and an angle of incidence of light from the firstback surface side light source on the back surface side main surface ofthe first liquid crystal panel is the same as an angle of incidence oflight from the second back surface side light source on the back surfaceside main surface of the first liquid crystal panel.

(10) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), (2), (3), (4), (5), (6), (7),(8), or (9), and the first liquid crystal panel further includes a firstsupport substrate on a back surface side of the polymer dispersed liquidcrystal, and a second support substrate on a viewing surface side of thepolymer dispersed liquid crystal.

(11) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (10), the first liquid crystalpanel further includes an alignment film at least one of between thefirst support substrate and the polymer dispersed liquid crystal orbetween the second support substrate and the polymer dispersed liquidcrystal, and the alignment film is a horizontal alignment filmconfigured to align the liquid crystal components in a directionparallel to a surface of the alignment film.

(12) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (11), and the liquid crystalcomponents have a positive anisotropy of dielectric constant.

(13) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (10), (11), or (12), and the firstliquid crystal panel further includes a transparent resin plate on aback surface side of the first support substrate.

(14) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (10), (11), (12), or (13), and thefirst liquid crystal panel further includes an anisotropic lightdiffusion film having a function to transmit light in a front view andscatter light in an oblique view on at least one of a back surface sideof the first support substrate or a viewing surface side of the secondsupport substrate.

(15) In an embodiment of the present invention, the liquid crystaldisplay device includes the structure (1), (2), (3), (4), (5), (6), (7),(8), (9), (10), (11), (12), (13), or (14), and the second liquid crystalpanel includes, sequentially from its back surface side toward itsviewing surface side, a third support substrate, a liquid crystal layer,a fourth support substrate, and an anisotropic light reflection filmhaving a function to transmit light in a front view and reflect light inan oblique view.

The present invention can provide a liquid crystal display devicecapable of switching between a transparent state and a scattering state,reducing or preventing a decrease in transmittance in the transparentstate, and reducing or preventing a decrease in luminance in the panelcentral portion in the scattering state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a schematic cross-sectional view of a liquidcrystal display device of Embodiment 1.

FIG. 2A is a schematic cross-sectional view of a transparent state of afirst liquid crystal panel in the liquid crystal display device ofEmbodiment 1.

FIG. 2B is a schematic cross-sectional view of a scattering state of thefirst liquid crystal panel in the liquid crystal display device ofEmbodiment 1.

FIG. 3 is a block diagram of the overall structure of the liquid crystaldisplay device of Embodiment 1.

FIG. 4 is a view of the structure of a single frame period in the liquidcrystal display device of Embodiment 1.

FIG. 5 is a schematic cross-sectional view of a second liquid crystalpanel in the liquid crystal display device of Embodiment 1.

FIG. 6 is a schematic cross-sectional view of a liquid crystal displaydevice of Embodiment 2.

FIG. 7 is a schematic cross-sectional view of a liquid crystal displaydevice of Modified Example 1.

FIG. 8 is a schematic cross-sectional view of a liquid crystal displaydevice of Modified Example 2.

FIG. 9 is a schematic perspective view of a light-shielding louver inthe liquid crystal display device of Modified Example 2.

FIG. 10A is an example of a schematic cross-sectional view of a liquidcrystal display device of Modified Example 3.

FIG. 10B is another example of a schematic cross-sectional view of theliquid crystal display device of Modified Example 3.

FIG. 10C is yet another example of a schematic cross-sectional view ofthe liquid crystal display device of Modified Example 3.

FIG. 10D is yet another example of a schematic cross-sectional view ofthe liquid crystal display device of Modified Example 3.

FIG. 11A is a schematic perspective view of an anisotropic lightdiffusion film in the liquid crystal display device of Modified Example3.

FIG. 11B is a schematic cross-sectional view of the anisotropic lightdiffusion film in the liquid crystal display device of Modified Example3.

FIG. 12 is another schematic perspective view of the anisotropic lightdiffusion film in the liquid crystal display device of Modified Example3.

FIG. 13A is another example of a schematic cross-sectional view of theanisotropic light diffusion film in the liquid crystal display device ofModified Example 3.

FIG. 13B is yet another example of a schematic cross-sectional view ofthe anisotropic light diffusion film in the liquid crystal displaydevice of Modified Example 3.

FIG. 14 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-2.

FIG. 15A is a graph of angle dependence of the transmittance of alight-shielding louver sheet in the liquid crystal display device ofExample 1-2.

FIG. 15B is an enlarged view of a region surrounded by the rectangle inthe graph of FIG. 15A.

FIG. 15C is a schematic view showing a method of determining the angledependence of the transmittance of the light-shielding louver sheet inthe liquid crystal display device of Example 1-2.

FIG. 16 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-3.

FIG. 17 is a schematic view showing a method of determining the angledependence of the transmittance of an optical film.

FIG. 18 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-4.

FIG. 19 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-5.

FIG. 20 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 2-1.

FIG. 21 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 2-2.

FIG. 22 is a schematic cross-sectional view of a liquid crystal displaydevice of Comparative Example 1.

FIG. 23 is a schematic view showing the evaluation of LED bulbs.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in more detail based on the followingembodiments with reference to the drawings. The present invention is notlimited to these embodiments.

Definition of Terms

Herein, the “viewing surface side” refers to the side that is closer tothe screen (display surface) of the polymer dispersed liquid crystaldisplay device. The “back surface side” is the side that is farther fromthe screen (display surface) of the polymer dispersed liquid crystaldisplay device.

Embodiment 1

FIG. 1 is an example of a schematic cross-sectional view of a liquidcrystal display device of Embodiment 1. As shown in FIG. 1 , a liquidcrystal display device 1 of the present embodiment includes,sequentially from its viewing surface side toward its back surface side,a first liquid crystal panel 11, a first light source 31X as the lightsource, a second liquid crystal panel 12, and a backlight 50.

FIG. 2A is a schematic cross-sectional view of the transparent state ofthe first liquid crystal panel in the liquid crystal display device ofEmbodiment 1. FIG. 2B is a schematic cross-sectional view of thescattering state of the first liquid crystal panel in the liquid crystaldisplay device of Embodiment 1. FIG. 2A and FIG. 2B each are a schematiccross-sectional view taken along line X1-X2 in FIG. 1 . As shown in FIG.2A and FIG. 2B, the first liquid crystal panel 11 includes a polymerdispersed liquid crystal 300 containing a polymer network 310 and liquidcrystal components 320 and is switchable between the transparent stateand the scattering state. Including the polymer dispersed liquid crystal300, the first liquid crystal panel 11 can display images without apolarizing plate, reducing or preventing a decrease in transmittance inthe transparent state.

As shown in FIG. 1 , the first light source 31X irradiates a backsurface side main surface 11P of the first liquid crystal panel 11 withlight from an oblique direction. This mode can reduce or preventattenuation of light in the central portion of the liquid crystal panelas compared with a case where light from the first light source 31Xtravels inside the first liquid crystal panel 11 or the polymerdispersed liquid crystal 300, further reducing or preventing a decreasein luminance (in particular, front luminance) of the panel centralportion in the scattering state. As a result, the display screen can beincreased in size. Herein, the back surface side main surface of thefirst liquid crystal panel refers to the surface of the first liquidcrystal panel closer to the light sources. The panel central portionrefers to the central portion of the display screen of the first liquidcrystal panel. The phrase “within the panel plane” refers to within thedisplay screen of the first liquid crystal panel.

For example, the liquid crystal display device of JP 2016-85452 A,employing a system of guiding light from the FSC-driven light sourcedisposed along a side of the liquid crystal panel to the inside of thelight modulation layer (specifically, polymer dispersed liquid crystal),could guide light for substantially only about 10 cm if it included a12.3-inch liquid crystal panel and light was incident from a long sideof the panel.

The liquid crystal display device would be able to switch between thetransparent display and the color display in a 19-inch liquid crystalpanel (30 cm in length×40 cm in width) by guiding light from theFSC-driven light source to the inside of the panel. With this size ofthe panel, however, the luminance in the central portion of the liquidcrystal panel may be significantly low as a result of loss of light dueto a factor such as diffraction or scattering by the TFTs or the polymerdispersed liquid crystal (PDLC) inside the panel. Specifically, theliquid crystal display device can merely guide light for substantiallyabout 20 cm when the light is incident on a short side of the liquidcrystal panel. The system of irradiating the back surface side mainsurface 11P of the first liquid crystal panel 11 with light from anoblique direction is also referred to as an oblique light incidencesystem, and a system of guiding light to the inside of the light guideplate or the panel is referred to as a light guide system. Hereinafter,the liquid crystal display device 1 of the present embodiment isdescribed in more detail.

As shown in FIG. 2A and FIG. 2B, the first liquid crystal panel 11includes a first substrate 100 as one of the pair of substrates, thepolymer dispersed liquid crystal 300, and a second substrate 200 as theother of the pair of substrates. The first substrate 100 includes afirst support substrate 110 and pixel electrodes 120. The secondsubstrate 200 includes a second support substrate 210 and a commonelectrode 220.

Preferably, the first liquid crystal panel 11 includes thin filmtransistors (TFTs). Light emitted from the first light source 31X isattenuated in some cases due to a factor such as diffraction orscattering by the TFTs inside the liquid crystal panel. The liquidcrystal display device 1 of the present embodiment can reduce suchattenuation of light by the TFTs even when the first liquid crystalpanel 11 includes the TFTs since the first light source 31X irradiatesthe back surface side main surface 11P of the first liquid crystal panel11 with light from an oblique direction. Thus, the liquid crystaldisplay device 1 can effectively reduce or prevent a decrease inluminance of the panel central portion in the scattering state. Thefollowing describes a mode in which the first liquid crystal panel(specifically, first substrate 100) includes TFTs, but the liquidcrystal display device is not limited to this mode.

The first substrate 100 includes TFTs which are switching elements usedto switch between ON and OFF of pixels in the first liquid crystal panel11. In the present embodiment, the structure of the first substrate 100for a TN mode is described.

The first substrate 100 includes, sequentially from its back surfaceside toward its viewing surface side, the first support substrate 110,parallel gate lines, a gate insulator, parallel source lines extendingin a direction in which they intersect the gate lines, an interlayerinsulating film, and the pixel electrodes 120. The gate lines and thesource lines are formed in a grid pattern that defines the pixels. TFTsas switching elements are disposed at the respective intersections ofthe gate lines and the source lines. The regions each surrounded byadjacent two gate lines and adjacent two source lines are provided withthe respective pixel electrodes 120.

Each TFT is a three-terminal switch that is connected to thecorresponding gate line and the corresponding source line, and includesa gate electrode that protrudes from (is part of) the corresponding gateline, a source electrode that protrudes from (is part of) thecorresponding source line, a drain electrode connected to thecorresponding pixel electrode, and a thin film semiconductor layer. Thesource electrode and the drain electrode are disposed in the same sourceline layer as the source lines. The gate electrode is disposed in thesame gate line layer as the gate lines.

The thin film semiconductor layer of each TFT is composed of, forexample, a high-resistance semiconductor layer formed from a materialsuch as amorphous silicon or polysilicon, and a low-resistancesemiconductor layer formed from a material such as n+ amorphous siliconobtained by doping amorphous silicon with an impurity such asphosphorus. The thin film semiconductor layer may be an oxidesemiconductor layer such as a zinc oxide semiconductor layer. Examplesof the oxide semiconductor layer include an In—Ga—Zn—O (indium galliumzinc oxide) layer which is an oxide semiconductor layer containingindium (In), gallium (Ga), zinc (Zn), and oxygen (O) as the maincomponents. With such In—Ga—Zn—O-TFTs, the effect of increasing theresolution and the effect of reducing the power consumption can beachieved, and a higher writing speed than that in conventional displaydevices can be achieved. The same effects can be achieved also when anoxide semiconductor layer is used which contains at least one of indium,gallium, zinc, copper (Cu), silicon (Si), tin (Sn), aluminum (Al),calcium (Ca), germanium (Ge), or lead (Pb).

The first support substrate 110 and the second support substrate 210 arepreferably transparent substrates. Examples thereof include glasssubstrates and plastic substrates.

The gate insulator is, for example, an inorganic insulating film. Theinorganic insulating film may be, for example, an inorganic film(relative dielectric constant (relative permittivity) ε=5 to 7) such asa silicon nitride (SiNx) film or a silicon oxide (SiO₂) film, or a stackof such films.

The gate line layer and the source line layer each are, for example, asingle or multi-layer of a metal such as copper, titanium, aluminum,molybdenum, or tungsten, or an alloy of any of these metals. The gatelines, the source lines, and the conductive lines and electrodes of theTFTs are formed by forming a single or multiple layers of a metal suchas copper, titanium, aluminum, molybdenum, or tungsten, or an alloy ofany of these metals by a technique such as sputtering, and patterningthe layer(s) by a technique such as photolithography. For efficientproduction, the conductive lines and electrodes to be in the same layerare formed from the same material.

The interlayer insulating film is, for example, an inorganic insulatingfilm. The inorganic insulating film may be, for example, an inorganicfilm (dielectric constant ε=5 to 7) such as a silicon nitride (SiNx)film or a silicon oxide (SiO₂) film, or a stack of such films.

The pixel electrodes 120 each are a planar (solid) electrode disposed ina corresponding region surrounded by adjacent two gate lines andadjacent two source lines. Each pixel electrode 120 is electricallyconnected to the corresponding source line via the thin filmsemiconductor layer of the corresponding TFT. The pixel electrode 120 isset at an electrical potential corresponding to the data signal suppliedvia the corresponding TFT.

The common electrode 220 is formed on almost the entire surface of thesecond support substrate 210 across the boundaries of the pixels. Acommon signal of a constant value is supplied to the common electrode220, so that the common electrode 220 is at a constant electricalpotential.

The pixel electrodes 120 and the common electrode 220 are formed from,for example, indium tin oxide (ITO) or indium zinc oxide (IZO).

The polymer dispersed liquid crystal 300 contains the polymer network310 and the liquid crystal components 320 and is held between the firstsubstrate 100 and the second substrate 200. In the polymer dispersedliquid crystal 300, fibrous matrices of a cured product of aphotopolymerizable liquid crystal compound are aggregated to form thethree-dimensionally continuous polymer network 310, and the liquidcrystal components 320 are phase-separated and dispersed within thepolymer network 310.

The polymer dispersed liquid crystal 300 contains the polymer network310 formed from the cured product of the photopolymerizable liquidcrystal compound, and the liquid crystal components 320. The polymerdispersed liquid crystal 300 is in the transparent state with no voltageapplied and is in the scattering state with voltage applied. This modeenables a display device that uses no polarizing plate. Morespecifically, the polymer dispersed liquid crystal 300 is in thetransparent state with no voltage applied, and shifts into thescattering state with voltage applied as the alignment of the liquidcrystal components 320 is changed.

The state “with no voltage applied” means when the voltage applied tothe polymer dispersed liquid crystal 300 is lower than the thresholdvoltage (including no voltage application). The state “with voltageapplied” means when the voltage applied to the polymer dispersed liquidcrystal 300 is equal to or higher than the threshold voltage. The statewith no voltage applied is also referred as a no voltage applicationstate, while the state with voltage applied is also referred to as avoltage application state.

Hereinafter, the alignment of the liquid crystal components 320 in thetransparent state and that in the scattering state are described withreference to FIG. 2A and FIG. 2B. FIG. 2A and FIG. 2B show the centralportion of the first liquid crystal panel 11.

As shown in FIG. 2A, with no voltage applied, preferably, the alignmentazimuths of the polymer network 310 and the liquid crystal components320 are substantially the same as each other. FIG. 2A shows a case whereboth the polymer network 310 and the liquid crystal components 320 arehomogeneously aligned relative to the main surfaces of the firstsubstrate 100 and the second substrate 200. With no voltage applied, inall the directions including the thickness direction of the polymerdispersed liquid crystal 300, there is almost no difference inextraordinary refractive index ne between the liquid crystal components320 and the polymer network 310 and almost no difference in ordinaryrefractive index no between the liquid crystal components 320 and thepolymer network 310. Thus, light emitted from the light source passesthrough the polymer dispersed liquid crystal 300, so that the liquidcrystal panel is in the transparent state. Such a state where there isalmost no difference in extraordinary refractive index ne between theliquid crystal components 320 and the polymer network 310 and almost nodifference in ordinary refractive index no between the liquid crystalcomponents 320 and the polymer network 310 in all the directionsincluding the thickness direction of the polymer dispersed liquidcrystal 300 is also considered as a state where the refractive index ofthe liquid crystal components 320 and that of the polymer network 310match.

The transparent state is a state of being transparent to light. Forexample, the polymer dispersed liquid crystal 300 in the transparentstate may have a transmittance of 80% or higher or 90% or higher. Theupper limit of the transmittance of the polymer dispersed liquid crystal300 in the transparent state is, for example, 100%. In the presentembodiment, the polymer dispersed liquid crystal 300 in the transparentstate is transparent to visible light. Herein, the transmittance of thepolymer dispersed liquid crystal in the transparent state refers to aparallel light transmittance of the polymer dispersed liquid crystal inthe transparent state. The transmittance of the polymer dispersed liquidcrystal in the transparent state can be measured in the followingmanner, for example. The luminance is measured with thespectroradiometer (SR-UL1) available from Topcon Technohouse Corporationat a light acceptance angle of 2° when a first liquid crystal panelincluding a polymer dispersed liquid crystal and with no voltage appliedis placed on a common backlight including a halogen lamp as a lightsource (i.e., light source for liquid crystal display devices) and whennothing is placed on the backlight. The measurement wavelength is about550 nm, which is the wavelength at which the luminous reflectance Yvalue representing the visual sensitivity of the human eye is highest.The luminance measured when the first liquid crystal panel with novoltage applied is placed on the backlight is divided by the luminancemeasured when nothing is placed on the backlight, so that thetransmittance of the polymer dispersed liquid crystal in the transparentstate can be determined.

As shown in FIG. 2B, with voltage applied, the molecules of the polymernetwork 310 are aligned horizontally to the main surfaces of the firstsubstrate 100 and the second substrate 200, while the liquid crystalcomponents 320 are aligned in the direction vertical to the surfaces ofthe first substrate 100 and the second substrate 200. With voltageapplied, electric fields generated in the polymer dispersed liquidcrystal 300 change the alignment azimuth of the liquid crystalcomponents 320, while having no influence on the polymer network 310.Thus, in all the directions including the thickness direction of thepolymer dispersed liquid crystal 300, the difference in extraordinaryrefractive index ne between the liquid crystal components 320 and thepolymer network 310 and the difference in ordinary refractive index nobetween the liquid crystal components 320 and the polymer network 310are large. Unpolarized light emitted from the first light source 31X andincident on the polymer dispersed liquid crystal 300 from an obliquedirection is scattered without dependence on polarization differentlyfrom the case where the unpolarized light is vertically incident on thepolymer dispersed liquid crystal 300, so that the polymer dispersedliquid crystal 300 is in the highly scattering state. Such a state wherethe difference in extraordinary refractive index ne between the liquidcrystal components 320 and the polymer network 310 and the difference inordinary refractive index no between the liquid crystal components 320and the polymer network 310 are large in all the directions includingthe thickness direction of the polymer dispersed liquid crystal 300 isalso considered as a state where the refractive index of the liquidcrystal components 320 and that of the polymer network 310 mismatch.

The scattering state is a state of scattering light. The polymerdispersed liquid crystal 300 in the scattering state may have atransmittance of 50% or lower, for example. The lower limit of thetransmittance of the polymer dispersed liquid crystal 300 in thescattering state is, for example, 0% to 1%. Herein, the transmittance ofthe polymer dispersed liquid crystal in the scattering state refers to aparallel light transmittance of the polymer dispersed liquid crystal inthe scattering state. The transmittance of the polymer dispersed liquidcrystal in the scattering state can be measured in the following manner,for example. The luminance is measured with the spectroradiometer(SR-UL1) available from Topcon Technohouse Corporation at a lightacceptance angle of 2° when a first liquid crystal panel including apolymer dispersed liquid crystal and with voltage applied is placed on acommon backlight including a halogen lamp as a light source (i.e., lightsource for liquid crystal display devices) and when nothing is placed onthe backlight. The measurement wavelength is about 550 nm, which is thewavelength at which the luminous reflectance Y value representing thevisual sensitivity of the human eye is highest. The luminance measuredwhen the first liquid crystal panel with voltage applied is placed onthe backlight is divided by the luminance measured when nothing isplaced on the backlight, so that the transmittance of the polymerdispersed liquid crystal in the scattering state can be measured.

The haze showing the light scattering ratio of the polymer dispersedliquid crystal 300 in the scattering state varies based on the voltageapplied, and may be, for example, 80% or higher or 90% or higher. Theupper limit of the haze showing the light scattering ratio of thepolymer dispersed liquid crystal 300 in the scattering state is, forexample, 90% to 100%. In the present embodiment, the polymer dispersedliquid crystal 300 in the scattering state scatters visible light. Thepolymer dispersed liquid crystal 300 in the scattering state istherefore in the same condition as frosted glass. Herein, the haze ismeasured by a method in conformity with JIS K 7136. The haze is measuredwith, for example, the haze meter “Haze Meter NDH2000” available fromNippon Denshoku Industries Co., Ltd. using a halogen lamp as a lightsource.

A liquid crystal panel that provides the transparent state with novoltage applied and provides the scattering state with voltage appliedis also referred to as a reverse mode liquid crystal panel. Whenunpolarized light is vertically incident on a common reverse mode liquidcrystal panel, the transmittance in the scattering state is as high asabout 50% since only one of s-polarized light and p-polarized light isscattered, which means that scattering of light is insufficient. This ispresumably because when light from a light source is vertically incidenton a main surface of a reverse mode liquid crystal panel, the mismatchof the refractive index of the liquid crystal components and therefractive index of the polymer network is associated only with one ofs-polarized light and p-polarized light. In contrast, in the presentembodiment, presumably, light is incident on the back surface side mainsurface 11P of the first liquid crystal panel 11 from an obliquedirection, so that the mismatch of the refractive index of the liquidcrystal components and the refractive index of the polymer network isassociated with both s-polarized light and p-polarized light, causing ahigher degree of scattering. The present embodiment enables a higherdegree of scattering than a reverse mode liquid crystal panel with apolymer dispersed liquid crystal containing a chiral agent, for example.

The liquid crystal display device 1 varies the difference inextraordinary refractive index ne between the liquid crystal components320 and the polymer network 310 in the polymer dispersed liquid crystal300 and the difference in ordinary refractive index no between theliquid crystal components 320 and the polymer network 310 to adjust theamount of light passing through the first liquid crystal panel 11. Theliquid crystal display device 1 therefore requires no polarizing platewhich is required in a common liquid crystal display device.

The photopolymerizable liquid crystal compound for formation of thepolymer network 310, for example, exhibits a liquid crystal phase atroom temperature to form a miscible blend with the liquid crystalcomponents 320, and is phase-separated from the liquid crystalcomponents 320 after it is cured by ultraviolet irradiation to form apolymer.

Examples of the photopolymerizable liquid crystal compound includemonomers having a substituent such as a biphenyl group, a terphenylgroup, a naphthalene group, a phenylbenzoate group, an azobenzene group,or a derivative of any of these groups (hereinafter, they are alsoreferred to as mesogen groups); a photoreactive group such as acinnamoyl group, a chalcone group, a cinnamylidene group, aβ-(2-phenyl)acryloyl group, a cinnamic acid group, or a derivative ofany of these groups; and a polymerizable group such as an acrylate,methacrylate, maleimide, N-phenylmaleimide, or siloxane group. Thepolymerizable group is preferably an acrylate group. The number ofpolymerizable groups per molecule of the photopolymerizable liquidcrystal compound is not limited, but is preferably 1 or 2.

The liquid crystal components 320 may not have a polymerizable groupsuch as an acrylate, methacrylate, maleimide, N-phenyl maleimide, orsiloxane group.

In the present embodiment, the anisotropy of dielectric constant (As) ofthe liquid crystal components 320 defined by the following formula (L)may be positive or negative, but is preferably positive when thelater-described alignment films 410 and 420 are horizontal alignmentfilms. This mode can effectively simultaneously achieve a high degree ofscattering and low-voltage driving. Liquid crystal components (liquidcrystal molecules) having a positive anisotropy of dielectric constantare aligned in the direction parallel to the electric field direction.Liquid crystal components (liquid crystal molecules) having a negativeanisotropy of dielectric constant are aligned in the direction verticalto the electric field direction. The liquid crystal components (liquidcrystal molecules) having a positive anisotropy of dielectric constantare also referred to as positive liquid crystals. Liquid crystalcomponents (liquid crystal molecules) having a negative anisotropy ofdielectric constant are also referred to as negative liquid crystals.The long axis direction of each liquid crystal component (liquid crystalmolecule) corresponds to the slow axis direction. The long axisdirection of each liquid crystal component (liquid crystal molecule)with no voltage applied is also referred to as the initial alignmentdirection of the liquid crystal component (liquid crystal molecule).

Δε=(dielectric constant in long axis direction of liquid crystalcomponent (liquid crystal molecule))−(dielectric constant in short axisdirection of liquid crystal component (liquid crystal molecule)) (L)

The liquid crystal components 320 can be, for example, a tolan-typeliquid crystal material (liquid crystal material having a —C≡C— bond(carbon-carbon triple bond) as a linking group).

The liquid crystal components 320 have an anisotropy of refractive indexΔn of 0.18 or higher and 0.24 or lower. Preferably, the liquid crystalcomponents 320 have an anisotropy of dielectric constant Δε of 15 orhigher and 25 or lower, and the liquid crystal components 320 have arotational viscosity γ1 of 100 mPa·s or higher and 300 mPa·s or lower.This mode can simultaneously achieve a high degree of scattering andlow-voltage driving, while achieving a response speed equal to that of acommon liquid crystal display device containing no polymer network. Thiseffect can be achieved when the anisotropy of refractive index Δn, theanisotropy of dielectric constant Δε, and the rotational viscosity γ1 ofthe liquid crystal components 320 all fall within the respective rangesabove.

Specific examples of the tolan-type liquid crystal material includeliquid crystal materials having a structure represented by the followingformula (L1).

In the formula, Q₁ and Q₂ each independently represent an aromatic ringgroup, X represents a fluorine group or a cyano group, and n₁ and n₂each independently represent 0 or 1.

The symbols n₁ and n₂ in the formula (L1) are not 0 at the same time. Inother words, the sum of n₁ and n₂ is 1 or 2.

The aromatic ring groups in the formula (L1) may have a substituent.

In the formula (L1), preferably, Q₁ and Q₂ each independently have anyone of the structures represented by the following formulas (L2-1) to(L2-7).

Specific examples of the structure represented by the formula (L1) inthe liquid crystal material include the following structures.

Preferably, the weight ratio of the liquid crystal components 320 to thepolymer network 310, i.e., liquid crystal component:polymer network, is90:10 to 97:3. In other words, preferably, the weight of the liquidcrystal components 320 relative to the polymer network 310 is 90 or moreand 97 or less, and when the weight of the liquid crystal components 320is 90 or more, the weight of the polymer network 310 is 10 or less,while when the weight of the liquid crystal components 320 is 97 orless, the weight of the polymer network 310 is 3 or more. This mode caneffectively simultaneously achieve a high degree of scattering andlow-voltage driving. When the weight of the polymer network 310 relativeto the liquid crystal components 320 is more than 10, a high degree ofscattering can be achieved, but the driving voltage is high. When theweight of the polymer network 310 relative to the liquid crystalcomponents 320 is less than 3, the driving voltage can be reduced but ahigh degree of scattering may not be achieved.

Preferably, the first liquid crystal panel 11 includes an alignment filmbetween the polymer dispersed liquid crystal 300 and at least one of thepair of substrates (first substrate 100 and second substrate 200)holding the polymer dispersed liquid crystal 300 in between. This modecan cause the alignment film to mainly control the alignment of theliquid crystal components 320 in the polymer dispersed liquid crystal300 when the voltage applied to the polymer dispersed liquid crystal 300is lower than the threshold voltage (including no voltage application).

The following describes a mode in which a first alignment film 410 isdisposed between the first substrate 100 and the polymer dispersedliquid crystal 300 and a second alignment film 420 is disposed betweenthe second substrate 200 and the polymer dispersed liquid crystal 300,but the first liquid crystal panel 11 is not limited thereto. Forexample, an alignment film may be disposed only between the firstsubstrate 100 and the polymer dispersed liquid crystal 300 or betweenthe second substrate 200 and the polymer dispersed liquid crystal 300,meaning that an alignment film may not be disposed between the firstsubstrate 100 and the polymer dispersed liquid crystal 300 and betweenthe second substrate 200 and the polymer dispersed liquid crystal 300.For example, when the first liquid crystal panel 11 includes only one ofthe first alignment film 410 and the second alignment film 420 and thealignment film is a horizontal alignment film while the other substrateside is slippery (having zero anchoring), the liquid crystal components320 are in twisted horizontal alignment. This ultimately results in thesame alignment state as in the case where horizontal alignment films aredisposed on the respective sides.

The first alignment film 410 and the second alignment film 420 arelayers having been subjected to alignment treatment for controlling thealignment of the liquid crystal components 320 and the molecules of thephotopolymerizable liquid crystal compound, and may each be an alignmentfilm commonly used in the field of liquid crystal display devices, suchas a polyimide film. The first alignment film 410 and the secondalignment film 420 may each be a rubbing alignment film having beensubjected to rubbing treatment or a photoalignment film having beensubjected to photoalignment treatment. Hereinafter, the liquid crystalcomponents 320 and the photopolymerizable liquid crystal compound mayalso be simply referred to as liquid crystal molecules.

A rubbing alignment film is obtainable by, for example, forming a filmof an alignment film material containing a rubbing alignment filmpolymer on a substrate, and rubbing the surface of the film containing arubbing alignment film polymer with a roller wrapped with a piece ofcloth made of a material such as rayon or cotton at a constantrotational speed and with a constant distance between the roller and thesubstrate (rubbing method).

The rubbing alignment film polymer may be, for example, polyimide. Oneor two or more rubbing alignment film polymers may be used for therubbing alignment film.

The photoalignment film is obtainable by, for example, forming a film ofan alignment film material containing a photoalignable polymer with aphotoreactive functional group on a substrate, and irradiating the filmcontaining the photoalignable polymer with polarized ultraviolet lightto make the surface of the film anisotropic (photoalignment method).

The photoalignable polymer may be, for example, a photoalignable polymercontaining at least one photoreactive functional group selected from acyclobutane group, an azobenzene group, a chalcone group, a cinnamategroup, a coumarin group, a stilbene group, a phenolic ester group, and aphenylbenzoate group. One or two or more photoalignable polymers may beused for the photoalignment film. The photoalignable polymer may containa photoreactive functional group in its main chain or its side chain, orboth in its main chain and its side chain.

The photoalignable polymer may undergo any type of photoreaction.Preferred examples of the photoalignable polymer include those that canundergo photodecomposition, photorearrangement (preferably, photo-Friesrearrangement), photoisomerization, photodimerization, orphotocrosslinking. These polymers may be used alone or in combination oftwo or more. In particular, in terms of alignment stability, polymersthat can undergo photodecomposition at a wavelength of about 254 nm(main sensing wavelength) and polymers that can undergophotorearrangement at a wavelength of about 254 nm (main sensingwavelength) are preferred. Also, polymers that can undergophotoisomerization and polymers that can undergo photodimerization whichhave a photoreactive functional group in their side chain are preferred.

The photoalignable polymer may have any main chain structure. Preferredexamples thereof include a polyamic acid structure, a polyimidestructure, a poly(meth)acrylic acid structure, a polysiloxane structure,a polyethylene structure, a polystyrene structure, and a polyvinylstructure.

The first alignment film 410 and the second alignment film 420 each area horizontal alignment film that aligns the liquid crystal components320 in the direction parallel to its surface or a vertical alignmentfilm that aligns the liquid crystal components 320 in the directionvertical to its surface. Preferably, the first alignment film 410 andthe second alignment film 420 are horizontal alignment films. This modecan effectively simultaneously achieve a high degree of scattering andlow-voltage driving. More preferably, the first alignment film 410 andthe second alignment film 420 are horizontal alignment films, and theliquid crystal components 320 have a positive anisotropy of dielectricconstant. This mode can more effectively simultaneously achieve a highdegree of scattering and low-voltage driving.

When the first alignment film 410 and the second alignment film 420 arehorizontal alignment films and the voltage applied to the polymerdispersed liquid crystal 300 is lower than the threshold voltage(including no voltage application), the first alignment film 410 and thesecond alignment film 420 mainly control the liquid crystal components320 such that the long axes of the liquid crystal components 320 areparallel to the first alignment film 410 and the second alignment film420.

In other words, the liquid crystal components 320 are alignedhorizontally (homogeneously) to the first substrate 100 with no voltageapplied. When voltage is applied between the pixel electrodes 120 andthe common electrode 220, electric fields are generated in the polymerdispersed liquid crystal 300 and change the alignment of the liquidcrystal components 320, so that the amount of light passing through thepolymer dispersed liquid crystal 300 can be controlled. The liquidcrystal components 320 are horizontally aligned by the control force ofthe first alignment film 410 and the second alignment film 420 with novoltage applied between the pixel electrodes 120 and the commonelectrode 220. The liquid crystal components 320 are rotated by thevertical electric fields generated in the polymer dispersed liquidcrystal 300 with voltage applied between the pixel electrodes 120 andthe common electrode 220.

The phrase “the long axes of the liquid crystal components 320 areparallel to the first alignment film 410 and the second alignment film420” means that the tilt angle (including the pre-tilt angle) of theliquid crystal components 320 is 0° to 5°, preferably 0° to 3°, morepreferably 0° to 1°, relative to the first alignment film 410 and thesecond alignment film 420. The tilt angle of the liquid crystalcomponents 320 means the angle at which the long axis (optical axis) ofeach liquid crystal component 320 inclines from the surface of the firstalignment film 410 or the second alignment film 420.

When the first alignment film 410 and the second alignment film 420 arevertical alignment films and the voltage applied to the polymerdispersed liquid crystal 300 is lower than the threshold voltage(including no voltage application), the first alignment film 410 and thesecond alignment film 420 mainly control the liquid crystal moleculessuch that the long axes of the liquid crystal molecules areperpendicular to the first alignment film 410 and the second alignmentfilm 420.

In other words, the liquid crystal components 320 are aligned in thedirection vertical to the first substrate 100 with no voltage applied.When voltage is applied between the pixel electrodes 120 and the commonelectrode 220, electric fields are generated in the polymer dispersedliquid crystal 300 and change the alignment of the liquid crystalcomponents 320, so that the amount of light passing through the polymerdispersed liquid crystal 300 is controlled. The liquid crystalcomponents 320 are vertically aligned by the control force of the firstalignment film 410 and the second alignment film 420 with no voltageapplied between the pixel electrodes 120 and the common electrode 220.The liquid crystal components 320 are rotated by the vertical electricfields generated in the polymer dispersed liquid crystal 300 withvoltage applied between the pixel electrodes 120 and the commonelectrode 220.

The phrase “the long axes of the liquid crystal components 320 arevertical to the first alignment film 410 and the second alignment film420” means that the tilt angle (including the pre-tilt angle) of theliquid crystal components 320 is 86° to 90°, preferably 87° to 89°, morepreferably 87.5° to 89°, relative to the first alignment film 410 andthe second alignment film 420.

Next, the method of producing the first liquid crystal panel 11 of thepresent embodiment is described. The method of producing the firstliquid crystal panel 11 includes forming the first alignment film 410and the second alignment film 420, each having been subjected toalignment treatment, on one of the surfaces of the first substrate 100and one of the surfaces of the second substrate 200, respectively;injecting a composition containing the photopolymerizable liquid crystalcompound and a polymerization initiator between the first substrate 100and the second substrate 200 that have been disposed with the firstalignment film 410 and the second alignment film 420 facing each other;and forming the polymer network 310 while curing the photopolymerizableliquid crystal compound by irradiating the composition with light.

The first substrate 100 and the second substrate 200 can each beproduced by a method commonly used in the field of the liquid crystaldisplay devices.

In the forming of the alignment films, an alignment film material isapplied to each of the first substrate 100 and the second substrate 200to form the first alignment film 410 and the second alignment film 420.Examples of the application method include the inkjet method and theroll coater method. The first alignment film 410 and the secondalignment film 420 are then subjected to alignment treatment. Examplesof the alignment treatment include the rubbing treatment which rubs thealignment film surface with a roller, for example, and thephotoalignment treatment which irradiates the alignment film surfacewith light. The photoalignment treatment enables alignment treatmentwithout contact with the alignment film surface, and is thusadvantageous over the rubbing method in that it can reduce or preventstain or generation of dust, for example, during the alignmenttreatment. An alignment film having been subjected to the photoalignmenttreatment as the alignment treatment is also called a photoalignmentfilm.

The first alignment film 410 and the second alignment film 420 may besubjected to the rubbing treatment such that they can provideantiparallel alignment or parallel alignment.

The injecting includes injecting a composition containing thephotopolymerizable liquid crystal compound and a polymerizationinitiator between the first substrate 100 and the second substrate 200that have been disposed with the first alignment film 410 and the secondalignment film 420 facing each other. In the injecting, the liquidcrystal molecules near the first alignment film 410 are aligned in thealignment direction provided by the first alignment film 410, the liquidcrystal molecules near the second alignment film 420 are aligned in thealignment treatment direction provided by the second alignment film 420,and the liquid crystal molecules around the middle position between thefirst alignment film 410 and the second alignment film 420 are alignedsuch that the alignment azimuth thereof is continuously varied betweenthe first alignment film 410 and the second alignment film 420.

The polymerization initiator may be any conventionally known one, suchas Omnirad 184® (available from IGM Resins. B.V.) represented by thefollowing Chemical formula (IN1) and OXE03 (available from BASF SE)represented by the following chemical formula (IN2).

Preferably, the weight ratio of the liquid crystal components 320 to thephotopolymerizable liquid crystal compound in the composition is 90:10to 97:3. In other words, preferably, the weight of the liquid crystalcomponents 320 relative to the photopolymerizable liquid crystalcompound is 90 or more and 97 or less, and when the weight of the liquidcrystal components 320 is 90 or more, the weight of thephotopolymerizable liquid crystal compound is 10 or less, while when theweight of the liquid crystal components 320 is 97 or less, the weight ofthe photopolymerizable liquid crystal compound is 3 or more. This modecan effectively simultaneously achieve a high degree of scattering andlow-voltage driving. When the weight of the photopolymerizable liquidcrystal compound relative to the liquid crystal components 320 is morethan 10, a high degree of scattering can be achieved, but the drivingvoltage is high. When the weight of the photopolymerizable liquidcrystal compound relative to the liquid crystal components 320 is lessthan 3, the driving voltage can be reduced but a high degree ofscattering may not be achieved.

The irradiating with light includes irradiating the composition withlight to form the polymer network 310 while curing thephotopolymerizable liquid crystal compound. Here, when the liquidcrystal molecules are aligned in the injecting, the photopolymerizableliquid crystal compound exhibits a liquid crystalline phase. Thephotopolymerizable liquid crystal compound is cured through aphotopolymerization reaction when the composition is irradiated withlight in the irradiating with light, so that the alignment of thephotopolymerizable liquid crystal compound is fixed. Thephotopolymerizable liquid crystal compound thus forms the polymernetwork 310, which is incapable of responding to the electric fields.The molecules of the polymer network 310 formed from the cured productof the photopolymerizable liquid crystal compound are therefore notaligned in the electric field direction upon voltage application. Incontrast, the liquid crystal components 320 whose alignment is not fixedare aligned in the electric field direction upon voltage application.

Thus, with no voltage applied, the alignment direction of the polymernetwork 310 and the alignment direction of the liquid crystal components320 are both parallel to the first substrate 100 and the secondsubstrate 200. In this state, matching the refractive indices of themcauses the first liquid crystal panel 11 to be in the transparent state.Also, with voltage applied to the polymer dispersed liquid crystal 300by connecting a power supply to the pixel electrodes 120 and the commonelectrode 220, the liquid crystal components 320 are aligned in theelectric field direction. The refractive index of the liquid crystalcomponents 320 and the refractive index of the polymer network 310 thusmismatch in the interface therebetween to produce the light scatteringstate, causing the first liquid crystal panel 11 to shift into an opaquestate (scattering state).

The light used in the irradiating with light may be any light such asultraviolet light. Examples of the ultraviolet light include lighthaving a peak wavelength in a wavelength range of 340 nm or longer and390 nm or shorter, for example.

In the irradiating with light, preferably, the composition is irradiatedwith light having an irradiation intensity of 5 mW/cm² or higher and 50mW/cm² or lower. With an irradiation intensity of 5 mW/cm² or higher, amore sufficient degree of scattering can be achieved. With anirradiation intensity of 50 mW/cm² or lower, an increase in temperatureduring irradiation can be reduced or prevented, and the yield declineand property variation can be reduced or prevented.

Preferably, in the irradiating with light, the composition is irradiatedwith light with an irradiation dose of 0.5 J/cm² or more and 5 J/cm² orless. With an irradiation dose of 0.5 J/cm² or more, the polymerizationreaction of the photopolymerizable liquid crystal compound sufficientlyproceeds to reduce unreacted molecules of the photopolymerizable liquidcrystal compound, forming the polymer network 310. As a result, thehysteresis properties and the anti-image-sticking properties can beimproved. With an irradiation dose of 5 J/cm² or less, the productiontakt time can be improved.

The method of displaying an image on the first liquid crystal panel isdescribed. Preferably, the first liquid crystal panel 11 displays animage based on a field-sequential color (FSC) system, and the firstlight source 31X includes light-emitting elements (red light emittingdiodes (LEDs) 31R, green LEDs 31G, and blue LEDs 31B) configured to emitlight rays of colors different from one another as shown in FIG. 1 .Typically, in a liquid crystal display device providing color display,each pixel is divided into three sub-pixels, namely a red pixel providedwith a color filter transmitting red light, a green pixel provided witha color filter transmitting green light, and a blue pixel provided witha color filter transmitting blue light. The color filters in these threesub-pixels enable color display. The color filters absorb about ⅔ of thebacklight illumination applied to the liquid crystal panel. This causesa liquid crystal display device employing the color filter system tohave a low light use efficiency. In contrast, the liquid crystal displaydevice 1 displaying images by the FSC system and using the first lightsource 31X including light-emitting elements configured to emit lightrays of colors different from one another can provide color displaywithout any color filters. The liquid crystal display device 1 thereforecan achieve a higher light use efficiency than a liquid crystal displaydevice employing the color filter system and achieve a higher luminanceand low power consumption. Also, since color filters are not used, theliquid crystal display device 1 can be reduced in thickness.

In the first liquid crystal panel 11 employing the FSC system to displayan image, a single frame period, which is a display period of a singlescreen image, is divided into multiple fields. A field is also called asub-frame. Throughout the following description, the term “field” isused. For example, a single frame period is divided into a field thatdisplays a red screen image based on the red color component in an inputimage signal (red field), a field that displays a green screen imagebased on the green color component in the input image signal (greenfield), and a field that displays a blue screen image based on the bluecolor component in the input image signal (blue field). The primarycolors are displayed one by one as described above to display a colorimage on the liquid crystal panel.

As described above, the first liquid crystal panel 11 employing the FSCsystem to display an image provides color display by dividing a singleframe period into multiple fields such that different colors aredisplayed in different fields. This enables elimination of colorfilters. The liquid crystal display device 1 employing the FSC systemtherefore has a light use efficiency that is about triple the light useefficiency of the liquid crystal display device employing the colorfilter system. Thus, the liquid crystal display device employing the FSCsystem is suitable for an increase in luminance and reduction in powerconsumption.

FIG. 3 is a block diagram of the overall structure of the liquid crystaldisplay device of Embodiment 1. The liquid crystal display device 1 ofthe present embodiment includes a preprocessing unit 1000, a timingcontroller 2000, a gate driver 3100, a source driver 3200, a LED driver3300, the first liquid crystal panel 11, and the first light source 31X.One or both of the gate driver 3100 and the source driver 3200 may bedisposed in the first liquid crystal panel 11. Also, FIG. 3 does notinclude the second liquid crystal panel 12. The second liquid crystalpanel 12 has the same structure as the first liquid crystal panel 11,except that it is a common liquid crystal panel that provides colordisplay using the color filters provided in the second liquid crystalpanel 12 and the backlight provided on the back surface side of thesecond liquid crystal panel 12, not by displaying images based on theFSC system.

The first liquid crystal panel 11 includes a display portion 11A fordisplaying an image. The preprocessing unit 1000 includes a signalseparation circuit 1100, a data correction circuit 1200, a red fieldmemory 1300(R), a green field memory 1300(G), and a blue field memory1300(B).

In the present embodiment, the first light source 31X uses lightemitting diodes (LEDs) as the light-emitting elements. Specifically, asshown in FIG. 1 , the red LEDs 31R, the green LEDs 31G, and the blueLEDs 31B define the first light source 31X. In the present embodiment,the timing controller 2000, the gate driver 3100, and the source driver3200 define a liquid crystal panel driving unit, while the LED driver3300 defines a light source driving unit. The signal separation circuit1100 defines an input image data separation unit.

FIG. 4 is a view of the structure of a single frame period in the liquidcrystal display device of Embodiment 1. A single frame period is dividedinto a red field which displays a red screen image based on the redcomponent in an input image signal DIN, a green field which displays agreen screen image based on the green component in the input imagesignal DIN, and a blue field which displays a blue screen image based onthe blue component in the input image signal DIN. In the red field, thered LEDs 31R are turned on after an elapse of a predetermined period oftime from when the field starts. In the green field, the green LEDs 31Gare turned on after an elapse of a predetermined period of time fromwhen the field starts. In the blue field, the blue LEDs 31B are turnedon after an elapse of a predetermined period of time from when the fieldstarts.

During operation of the liquid crystal display device 1, these redfield, green field, and blue field are repeated. This causes the redscreen, the green screen, and the blue screen to be displayedrepeatedly, displaying the desired color image on the display portion11A. The order of the fields is not limited. The order of the fields maybe, for example, the blue field, the green field, and the red field. Thelength of the period during which the LED is turned on in each field maybe determined in consideration of the response property of the liquidcrystal.

As shown in FIG. 3 , in the display portion 11A, multiple (n number of)source lines (video signal lines) SL1 to SLn and multiple (m number of)gate lines (scanning signal lines) GL1 to GLm are arranged. Theintersections of the source line SL1 to SLn and the gate lines GL1 toGLm each are provided with a pixel forming portion 4. In other words,the display portion 11A includes multiple (n×m) pixel forming portions4. The pixel forming portions 4 are arranged in a matrix pattern todefine a pixel matrix with m rows×n columns. Hereinafter, each of thesource lines SL1 to SLn is also simply referred to as a source line SL,and each of the gate lines GL1 to GLm is also simply referred to as agate line GL.

Each pixel forming portion 4 includes a thin film transistor (TFT) 40which is a switching element whose gate terminal is connected to thegate line GL passing the corresponding intersection and whose sourceterminal is connected to the source line SL passing the intersection; apixel electrode 120 connected to the drain terminal of the TFT 40; thecommon electrode 220 and an auxiliary capacitance electrode 45 common tothe pixel forming portions 4; a liquid crystal capacitance 42 formed bythe pixel electrode 120 and the common electrode 220; and an auxiliarycapacitance 43 formed by the pixel electrode 120 and the auxiliarycapacitance electrode 45. The liquid crystal capacitance 42 and theauxiliary capacitance 43 define a pixel capacitance 46. In the displayportion 11A in FIG. 3 , only the components corresponding to a singlepixel forming portion 4 are shown.

The operation of the components in FIG. 3 is descried below. The signalseparation circuit 1100 in the preprocessing unit 1000 divides an inputimage signal DIN from an external device into red input grayscale data1R, green input grayscale data 1G, and blue input grayscale data 1B. Thedata correction circuit 1200 in the preprocessing unit 1000 corrects theinput grayscale data (red input grayscale data 1R, green input grayscaledata 1G, and blue input grayscale data 1B) outputted from the signalseparation circuit 1100 to data corresponding to the voltage to beapplied to the liquid crystal panel 11, and outputs the corrected dataas the application grayscale data (red field application grayscale data1 r, green field application grayscale data 1 g, and blue fieldapplication grayscale data 1 b). The data correction circuit 1200 isdescribed in more detail later.

The red field memory 1300(R), the green field memory 1300(G), and theblue field memory 1300(B) respectively store the red field applicationgrayscale data 1 r, the green field application grayscale data 1 g, andthe blue field application grayscale data 1 b which were outputted fromthe data correction circuit 1200.

The timing controller 2000 reads the red field application grayscaledata 1 r, the green field application grayscale data 1 g, and the bluefield application grayscale data 1 b respectively from the red fieldmemory 1300(R), the green field memory 1300(G), and the blue fieldmemory 1300(B). The timing controller 2000 then outputs a digital videosignal DV; a gate start pulse signal GSP and a gate clock signal GCKwhich are for controlling the operation of the gate driver 3100; asource start pulse signal SSP, a source clock signal SCK, and a latchstrobe signal LS which are for controlling the operation of the sourcedriver 3200; and an LED driver control signal S1 for controlling theoperation of the LED driver 3300.

The gate driver 3100 repeats supply of an active scanning signal to eachgate line GL based on the gate start pulse signal GSP and the gate clocksignal GCK from the timing controller 2000, with a single verticalscanning period taken as a single cycle.

The source driver 3200 receives the digital video signal DV, the sourcestart pulse signal SSP, the source clock signal SCK, and the latchstrobe signal LS from the timing controller 2000, and supplies a drivingvideo signal to each source line SL. At this time, the source driver3200 holds digital video signals DV sequentially generated in responseto generation of pulses of the source clock signals SCK and showing themagnitudes of voltage to be applied to the respective source lines SL.Then, in response to generation of pulses of the latch strobe signalsLS, the digital video signals DV held as above are converted to themagnitudes of analogue voltage. The converted magnitudes of analoguevoltage are simultaneously applied to the source lines SL1 to SLn asdriving video signals.

The LED driver 3300, based on the LED driver control signals S1 from thetiming controller 2000, outputs light source control signals S2 forcontrolling the states of the LEDs (red LEDs 31R, green LEDs 31G, andblue LEDs 31B) defining the first light source 31X. The first lightsource 31X appropriately switches the states (switches between turningon and off) of each LED based on the light source control signal S2. Inthe present embodiment, the state of each LED is switched as shown inFIG. 4 .

As described above, scanning signals are supplied to the gate lines GL1to GLm and driving video signals are supplied to the source lines SL1 toSLn, so that the states of each LED are appropriately switched. Thus, animage corresponding to the input image signal DIN is displayed on thedisplay portion 11A of the liquid crystal panel 11.

The first light source 31X includes the light-emitting elements (redLEDs 31R, green LEDs 31G, and blue LEDs 31B) configured to emit lightrays of colors different from one another. The first light source 31Xhas, for example, a rod-like shape in which the light-emitting elementsare aligned in a straight line.

Preferably, the liquid crystal display device 1 satisfies the following(formula 1-1):1 cm≤h11≤{a/(tan θ11)}  (formula 1-1)where a is calculated from the length 2 a [cm] of a long side of thefirst liquid crystal panel 11, h11 [cm] is the distance between thefirst liquid crystal panel 11 and the first light source 31X, and θ11[°] is the angle of incidence of light from the first light source 31X onthe back surface side main surface 11P of the first liquid crystal panel11. This mode increases the intensity of the front scattering componentsin the scattering state and enables further reduction or prevention of adecrease in luminance of the panel central portion in the scatteringstate, thus enabling even brighter display. Herein, the distance betweenthe first liquid crystal panel and the light source refers to thedistance from the first liquid crystal panel to the end of the lightsource closer to the first liquid crystal panel. θ11 refers to the angleof incidence of a light ray travelling along the path closest to thecenter of the first liquid crystal panel 11 among the light rays emittedfrom the first light source 31X.

As shown in FIG. 1 , the first light source 31X is disposedcorrespondingly to one edge portion 11X of a pair of edge portions 11Xand 11Y of the first liquid crystal panel 11 facing each other, theliquid crystal display device 1 further includes a second light source31Y that is disposed between the first liquid crystal panel 11 and thesecond liquid crystal panel 12 and correspondingly to the other edgeportion 11Y of the edge portions 11X and 11Y, the second light source31Y is configured to irradiate the back surface side main surface 11P ofthe first liquid crystal panel 11 with light from an oblique direction,and the angle of incidence θ11 of light from the first light source 31Xon the back surface side main surface 11P of the first liquid crystalpanel 11 is the same as the angle of incidence θ12 of light from thesecond light source 30Y on the back surface side main surface 11P of thefirst liquid crystal panel 11. This mode can reduce or prevent adecrease in luminance more evenly within the panel plane in thescattering state.

The second light source 31Y is the same as the first light source 31X,except that it is disposed in the other edge portion 11Y.

Preferably, the liquid crystal display device 1 satisfies the following(formula 1-2):1 cm≤h12≤{a/(tan θ12)}  (formula 1-2)where a is calculated from the length 2 a [cm] of a long side of thefirst liquid crystal panel 11, h12 [cm] is the distance between thefirst liquid crystal panel 11 and the second light source 31Y, and θ12[°] is the angle of incidence of light from the second light source 31Y onthe back surface side main surface 11P of the first liquid crystal panel11. This mode increases the intensity of the front scattering componentsin the scattering state and enables further reduction or prevention of adecrease in luminance of the panel central portion in the scatteringstate, thus enabling even brighter display. The symbol θ12 refers to theangle of incidence of a light ray travelling along the path closest tothe center of the first liquid crystal panel 11 among the light raysemitted from the second light source 31Y.

Preferably, the first light source 31X and the second light source 31Ysatisfy the following formulas (formula 1-3) and (formula 1-4):h11=h12  (formula 1-3)θ11=θ12  (formula 1-4).

This mode applies light from the first light source 31X and light fromthe second light source 31Y symmetrically to the central line of thefirst liquid crystal panel 11 parallel to the pair of edge portions 11Xand 11Y, thus enabling reduction or prevention of a decrease inluminance more evenly within the panel plane in the scattering state.

Preferably, the first light source 31X and the second light source 31Yin a front view are symmetrical about the central line of the firstliquid crystal panel 11 parallel to the pair of edge portions 11X and11Y. This mode can reduce or prevent a decrease in luminance more evenlywithin the panel plane in the scattering state.

Preferably, h11 and h12 and θ11 and θ12 are set such that light from thefirst light source 31X and light from the second light source 31Y reachthe central line of the first liquid crystal panel 11 parallel to thepair of edge portions 11X and 11Y. This mode can reduce or prevent adecrease in luminance more evenly within the panel plane in thescattering state.

When the first liquid crystal panel 11 is a 19-inch one, h11 and h12 arepreferably 3 cm or longer and 12 cm or shorter, more preferably 4 cm orlonger and 11 cm or shorter, still more preferably 5 cm or longer and 10cm or shorter. Also, θ11 and θ12 are preferably 51° or more and 63° orless, more preferably 53° or more and 61° or less, still more preferably55° or more and 59° or less.

Next, the second liquid crystal panel 12 is described. In the liquidcrystal display device 1 of the present embodiment, when the firstliquid crystal panel 11 is in the transparent state, an image on thesecond liquid crystal panel 12 can be observed from the viewing surfaceside.

FIG. 5 is a schematic cross-sectional view of a second liquid crystalpanel in the liquid crystal display device of Embodiment 1. As shown inFIG. 5 , the second liquid crystal panel 12 includes, sequentially fromits back surface side toward its viewing surface side, a firstpolarizing plate 510, a third substrate 600, a third alignment film 710,a liquid crystal layer 800 containing liquid crystal molecules, a fourthalignment film 720, a fourth substrate 900, and a second polarizingplate 520. The third substrate 600 includes a third support substrate610 and pixel electrodes 620. The fourth substrate 900 includes a fourthsupport substrate 910, a color filter layer 920, and a common electrode930.

In the present embodiment, a vertical alignment mode liquid crystaldisplay device is described in which the third substrate 600 includesthe pixel electrodes 620 and the fourth substrate 900 includes thecommon electrode 930. The display mode of the second liquid crystalpanel 12 is not limited thereto. The liquid crystal display device maybe a horizontal alignment mode liquid crystal display device in whichthe third substrate 600 or the fourth substrate 900 includes both thepixel electrodes and the common electrode. The vertical alignment modeis a mode that aligns the liquid crystal molecules in the directionsubstantially vertical to the main surfaces of the pair of substrates(the first substrate and the second substrate) with no voltage appliedto the liquid crystal layer. Examples of the mode include the verticalalignment (VA) mode and the twisted nematic (TN) mode. The horizontalalignment mode is a mode that aligns the liquid crystal molecules in thedirection substantially horizontal to the main surfaces of the pair ofsubstrates with no voltage applied to the liquid crystal layer. Examplesof the mode include the in-plane switching (IPS) mode and the fringefield switching (FFS) mode.

The phrase “substantially vertical” means that, for example, thepre-tilt angle of the liquid crystal molecules is 85° or greater and 90°or smaller relative to the main surface of one of the substrates. Thephrase “substantially horizontal” means that, for example, the pre-tiltangle of the liquid crystal molecules is 0° or greater and 5° or smallerrelative to the main surface of one of the substrates. The pre-tiltangle refers to the angle formed by the long axis of each liquid crystalmolecule with a surface of a substrate when the voltage applied to theliquid crystal layer is lower than the threshold voltage (including novoltage application), with the substrate surface being at 0° and theline normal to the substrate being at 90°. The main surface of asubstrate means a substrate surface.

In the present embodiment, light from the backlight 50 is incident onthe second liquid crystal panel 12 and the alignment of the liquidcrystal molecules in the liquid crystal layer 800 is switched, so thatthe amount of light passing through the second liquid crystal panel 12is controlled. The second liquid crystal panel 12 is a liquid crystaldisplay (LCD) panel.

The third support substrate 610 and the fourth support substrate 910 arepreferably transparent substrates, such as glass substrates or plasticsubstrates.

The pixel electrodes 620 are the same as the pixel electrodes 120 in thefirst liquid crystal panel 11. The common electrode 930 is the same asthe common electrode 220 in the first liquid crystal panel 11.

The color filter layer 920 includes red color filters, green colorfilters, and blue color filters. In each pixel, three sub-pixels, namelya sub-pixel with a red color filter, a sub-pixel with a green colorfilter, and a sub-pixel with a blue color filter, are arranged in astriped pattern.

Each of the red color filter, the green color filter, and the blue colorfilter is formed from, for example, a transparent resin containing apigment. Typically, each pixel is provided with a red color filter, agreen color filter, and a blue color filter in combination, and thedesired color is produced in each pixel by mixing the colors of thelight rays passing through the red color filter, the green color filter,and the blue color filter while controlling the amounts of the lightrays passing through the respective filters.

The third alignment film 710 and the fourth alignment film 720 have afunction to control the alignment of the liquid crystal molecules in theliquid crystal layer 800. When the voltage applied to the liquid crystallayer 800 is lower than the threshold voltage (including no voltageapplication), the alignment films mainly control the alignment of theliquid crystal molecules in the liquid crystal layer 800. The alignmentfilms can be formed from a material commonly used in the field of liquidcrystal display panels, such as a polymer with a polyimide structure inits main chain, a polymer with a polyamic acid structure in its mainchain, or a polymer with a polysiloxane structure in its main chain.

The liquid crystal layer 800 contains a liquid crystal material. Theamount of light passing through the liquid crystal layer 800 iscontrolled by applying voltage to the liquid crystal layer 800 to changethe alignment of the liquid crystal molecules in the liquid crystalmaterial based on the applied voltage.

The liquid crystal molecules may have a positive value or negative valueof the anisotropy of dielectric constant (As) which is defined by theformula (L).

The alignment of the liquid crystal molecules is switched by applicationof voltage between the pixel electrodes 620 and the common electrode 930holding the liquid crystal layer 800. With no voltage applied betweenthe pixel electrodes 620 and the common electrode 930, the thirdalignment film 710 and the fourth alignment film 720 control the initialalignment of the liquid crystal molecules. The state “with no voltageapplied between the pixel electrodes 620 and the common electrode 930”means that the voltage applied to the liquid crystal layer 800 is lowerthan the threshold voltage, including a state where voltage issubstantially not applied between the pixel electrodes 620 and thecommon electrode 930.

The second liquid crystal panel 12 may further include polarizing plateson the respective surfaces of the third substrate 600 and the fourthsubstrate 900 remote from the liquid crystal layer 800. Both polarizingplates are absorptive polarizers, and are preferably in crossed Nicolswhere the absorption axes thereof are perpendicular to each other.Preferably, the liquid crystal molecules in the liquid crystal layer 800with no voltage applied are homogeneously aligned in the directionparallel to the absorption axis of one of the polarizing plates. Thismode enables the liquid crystal panel 12 to operate in the normallyblack mode.

The backlight 50 may be any backlight that irradiates the second liquidcrystal panel 12 with light. The backlight 50 may be one usually used inthe field of liquid crystal display devices. The backlight 50 may be anyone that is disposed on the back surface of the second liquid crystalpanel 12 and can cause light produced in the backlight 50 to passthrough the transmission region of the second liquid crystal panel 12and then to be emitted toward the viewer. The backlight 50 may be adirect-lit backlight or an edge-lit backlight.

The backlight 50 includes, for example, a light source and a light guideplate. The light source may be any light source that emits lightincluding visible light, such as one that emits light including onlyvisible light or light including both visible light and ultravioletlight. In order to provide color display on the second liquid crystalpanel 12, a light source emitting white light is suitable. Suitablekinds of the light source include cold cathode fluorescent lamps (CCFLs)and light emitting diodes (LEDs). The light guide plate may be any onethat has a function to guide light incident on its edge surface to beuniformly emitted from its surface, and may be one usually used in thefield of liquid crystal display devices. The “visible light” as usedherein means light (electromagnetic waves) having a wavelength of 380 nmor longer and shorter than 800 nm. The backlight 50 may further utilizean optical sheet such as a diffuser plate or a prism sheet asappropriate.

Preferably, the distance b [cm] between the first liquid crystal panel11 and the second liquid crystal panel 12 is a [cm] or shorter, whereina is calculated from the length 2 a [cm] of a long side of the firstliquid crystal panel 11. This mode can reduce the thickness of theliquid crystal display device 1. This mode can also reduce the distancebetween the videos on the first liquid crystal panel 11 and the secondliquid crystal panel 12, enabling integrated visual effects in obliqueobservation of the liquid crystal display device 1. This mode issuitable for, for example, a case where characters are displayed asinformation on the first liquid crystal panel 11 and the second liquidcrystal panel 12.

Also preferably, the distance b [cm] between the first liquid crystalpanel 11 and the second liquid crystal panel 12 is longer than a [cm].This mode can increase the distance between the videos on the firstliquid crystal panel 11 and the second liquid crystal panel 12, enablingvisual effects with a spatial depth in oblique observation of the liquidcrystal display device 1.

When the first liquid crystal panel 11 is a 19-inch one and the secondliquid crystal panel is a 17-inch one, preferably, 2 a is 40 cm and b is10 cm or longer and 20 cm or shorter, more preferably 11 cm or longerand 19 cm or shorter, still more preferably 12 cm or longer and 18 cm orshorter.

As described above, the liquid crystal display device 1 of the presentembodiment includes a PDLC panel as the front panel (first liquidcrystal panel 11) and an LCD panel as the back surface panel (secondliquid crystal panel 12), i.e., is a dual display (PDLC panel+LCDpanel). The liquid crystal display device 1 irradiates the PDLC panelwith light from the FSC-driven light source from an oblique direction,and thus can achieve a favorable transparent transmittance (50% orhigher), an increase in size (for example, 19-inch size), and brightdisplay (high luminance) at the same time.

The liquid crystal display device 1 of the present embodiment has astructure including, as well as the components described above,components including external circuits such as a tape-carrier package(TCP) and a printed circuit board (PCB); optical films such as a viewingangle-increasing film and a luminance-increasing film; and a bezel(frame). Some components may be incorporated into another component.Components other than those described above are not particularly limitedand are not described here because such components can be those commonlyused in the field of liquid crystal display devices.

Embodiment 2

In the present embodiment, features unique to the present embodiment aremainly described, and the same features as those in the above embodimentare not described again. The present embodiment is substantially thesame as Embodiment 1, except that a back surface side light source isbetween the first light source 31X and the second liquid crystal panel12.

FIG. 6 is a schematic cross-sectional view of a liquid crystal displaydevice of Embodiment 2. As shown in FIG. 6 , preferably, the liquidcrystal display device 1 of the present embodiment includes a first backsurface side light source 32X as the above back surface side lightsource between the first light source 31X and the second liquid crystalpanel 12, and the first back surface side light source 32X irradiatesthe back surface side main surface 11P of the first liquid crystal panel11 with light from an oblique direction. This mode can further reduce adecrease in luminance (more specifically, front luminance) of the panelcentral portion in the scattering state. As a result, the display screencan be further increased in size.

Preferably, the first back surface side light source 32X includeslight-emitting elements (red LEDs 31R, green LEDs 31G, and blue LEDs31B) configured to emit light rays of colors different from one another.The first back surface side light source 32X has, for example, arod-like shape in which the light-emitting elements are aligned in astraight line.

Preferably, the liquid crystal display device 1 satisfies the following(formula 1-1) and (formula 2-1):1 cm≤h11≤{a/(tan θ11)}  (formula 1-1)θ11−θ21>10°  (formula 2-1)where a is calculated from the length 2 a [cm] of a long side of thefirst liquid crystal panel 11, h11 [cm] is the distance between thefirst liquid crystal panel 11 and the first light source 31X, θ11[° ] isthe angle of incidence of light from the first light source 31X on theback surface side main surface 11P of the first liquid crystal panel 11,and θ21[°] is the angle of incidence of light from the first backsurface side light source 32X on the back surface side main surface 11Pof the first liquid crystal panel 11. This mode increases the intensityof the front scattering components in the scattering state and enablesfurther reduction or prevention of a decrease in luminance of the panelcentral portion in the scattering state, thus enabling even brighterdisplay. The symbol 821 refers to the angle of incidence of a light raytravelling along the path closest to the center of the first liquidcrystal panel 11 among the light rays emitted from the light source 32X.

Preferably, the liquid crystal display device 1 satisfies the following(formula 1-2) and (formula 2-2):1 cm≤h12≤{a/(tan θ12)}  (formula 1-2)θ12−θ22>10°  (formula 2-2)where a is calculated from the length 2 a [cm] of a long side of thefirst liquid crystal panel 11, h12 [cm] is the distance between thefirst liquid crystal panel 11 and the second light source 31Y, θ12[° ]is the angle of incidence of light from the second light source 31Y onthe back surface side main surface 11P of the first liquid crystal panel11, and θ22[° ] is the angle of incidence of light from a second backsurface side light source 32Y on the back surface side main surface 11Pof the first liquid crystal panel 11. This mode increases the intensityof the front scattering components in the scattering state and enablesfurther reduction or prevention of a decrease in luminance of the panelcentral portion in the scattering state, thus enabling even brighterdisplay. The symbol 922 refers to the angle of incidence of a light raytravelling along the path closest to the center of the first liquidcrystal panel 11 among the light rays emitted from the light source 32Y.

As shown in FIG. 6 , the first back surface side light source 32X isdisposed correspondingly to the one edge portion 11X of the pair of edgeportions 11X and 11Y of the first liquid crystal panel 11 facing eachother, the liquid crystal display device 1 further includes the secondback surface side light source 32Y that is disposed between the firstliquid crystal panel 11 and the second liquid crystal panel 12 andcorrespondingly to the other edge portion 11Y of the edge portions 11Xand 11Y, the second back surface side light source 32Y is configured toirradiate the back surface side main surface 11P of the first liquidcrystal panel 11 from an oblique direction, and the angle of incidenceθ21 of light from the first back surface side light source 32X on theback surface side main surface 11P of the first liquid crystal panel 11is the same as the angle of incidence θ22 of light from the second backsurface side light source 32Y on the back surface side main surface 11Pof the first liquid crystal panel 11. This mode can reduce or prevent adecrease in luminance more evenly within the panel plane in thescattering state.

The second back surface side light source 32Y is the same as the firstback surface side light source 32X, except that it is disposed on theother edge portion 11Y.

Preferably, the liquid crystal display device 1 satisfies the following(formula 1-2) and (formula 2-2):1 cm≤h12≤{a/(tan θ12)}  (formula 1-2)θ12−θ22>10°  (formula 2-2)where a is calculated from the length 2 a [cm] of a long side of thefirst liquid crystal panel 11, h12 [cm] is the distance between thefirst liquid crystal panel 11 and the second light source 31Y, θ12[° ]is the angle of incidence of light from the second light source 31Y onthe back surface side main surface 11P of the first liquid crystal panel11, and θ22[° ] is the angle of incidence of light from the second backsurface side light source 32Y on the back surface side main surface 11Pof the first liquid crystal panel 11. This mode increases the intensityof the front scattering components in the scattering state and enablesfurther reduction or prevention of a decrease in luminance of the panelcentral portion in the scattering state, thus enabling even brighterdisplay.

Preferably, the first back surface side light source 32X and the secondback surface side light source 32Y satisfy the following formulas(formula 2-3) and (formula 2-4):h21=h22  (formula 2-3)θ21=θ22  (formula 2-4)where h21 [cm] is the distance between the first liquid crystal panel 11and the first back surface side light source 32X and h22 [cm] is thedistance between the first liquid crystal panel 11 and the second backsurface side light source 32Y. This mode applies light from the firstback surface side light source 32X and light from the second backsurface side light source 32Y symmetrically to the central line of thefirst liquid crystal panel 11 parallel to the pair of edge portions 11Xand 11Y, thus enabling reduction or prevention of a decrease inluminance more evenly within the panel plane in the scattering state.

Preferably, the first back surface side light source 32X and the secondback surface side light source 32Y in a front view are symmetrical aboutthe central line of the first liquid crystal panel 11 parallel to thepair of edge portions 11X and 11Y. This mode can reduce or prevent adecrease in luminance more evenly within the panel plane in thescattering state.

Preferably, the angles of incidence θ21 and θ22 are set such that lightfrom the first back surface side light source 32X and light from thesecond back surface side light source 32Y reach the central line of thefirst liquid crystal panel 11 parallel to the pair of edge portions 11Xand 11Y. This mode can reduce or prevent a decrease in luminance moreevenly within the panel plane in the scattering state.

Preferably, the distances h21 and h22 and the angles of incidence θ21and θ22 are set such that light from the first back surface side lightsource 32X and light from the second back surface side light source 32Yreach the central line of the first liquid crystal panel 11 parallel tothe pair of edge portions 11X and 11Y. This mode can reduce or prevent adecrease in luminance more evenly within the panel plane in thescattering state.

When the first liquid crystal panel 11 is a 19-inch one, the distancesh21 and h22 each are preferably 4 cm or longer and 13 cm or shorter,more preferably 5 cm or longer and 12 cm or shorter, still morepreferably 6 cm or longer and 11 cm or shorter. The angles of incidenceθ21 and θ22 are preferably 62° or greater and 74° or smaller, morepreferably 64° or greater and 72° or smaller, still more preferably 66°or greater and 70° or smaller.

The distance d between the first light source 31X and the first backsurface side light source 32X and the distance d between the secondlight source 31Y and the second back surface side light source 32Y eachare preferably 1 cm or longer and 6 cm or shorter, more preferably 2 cmor longer and 5 cm or shorter.

Modified Example 1

FIG. 7 is a schematic cross-sectional view of a liquid crystal displaydevice of Modified Example 1. FIG. 7 is a schematic cross-sectional viewtaken along line Y1-Y2 in FIG. 6 . As shown in FIG. 7 , the first liquidcrystal panel 11 may include a transparent resin plate 20 on the backsurface side of the first substrate 100. With the transparent resinplate 20, the first liquid crystal panel 11 can exhibit a higher degreeof strength. The size of the transparent resin plate 20 may be the sameas or greater than that of the first support substrate 110. Examples ofthe transparent resin plate 20 include acrylic plates.

Modified Example 2

FIG. 8 is a schematic cross-sectional view of a liquid crystal displaydevice of Modified Example 2. As shown in FIG. 8 , the liquid crystaldisplay device 1 may include a light-shielding louver 13 on the viewingsurface side of the first liquid crystal panel 11. This mode can achievelight shielding with the light source (particularly the LEDs definingthe light source) being unobservable in observation of the liquidcrystal display device from an oblique direction.

FIG. 9 is a schematic perspective view of a light-shielding louver inthe liquid crystal display device of Modified Example 2. Thelight-shielding louver 13 includes, as shown in FIG. 9 , a louver layer131 in which light-shielding layers 1311 and transparent layers 1312 arealternately arranged in the direction parallel to each other, and a pairof transparent films 132 holding the louver layer 131 in between. Thelight-shielding layers 1311 and the transparent layers 1312 include, forexample, a silicone resin.

Modified Example 3

FIG. 10A to FIG. 10D each are an example of a schematic cross-sectionalview of a liquid crystal display device of Modified Example 3. As shownin FIG. 10A to FIG. 10D, the first liquid crystal panel 11 may furtherinclude an anisotropic light diffusion film 14 having a function totransmit light in a front view while scattering light in an obliqueview, on at least one of the back surface side of the first supportsubstrate 110 or the viewing surface side of the second supportsubstrate 210. This mode can further reduce or prevent a decrease inluminance of the panel central portion in the scattering state.

For example, in a mode where the liquid crystal display device 1includes a pair of light sources (first light source 31X and secondlight source 31Y) as shown in FIG. 10A, the anisotropic light diffusionfilm 14 may be disposed on the back surface side of the first supportsubstrate 110. Also, in a mode where the liquid crystal display device 1includes a pair of light sources (first light source 31X and secondlight source 31Y) as shown in FIG. 10B, the anisotropic light diffusionfilm 14 may be disposed on the viewing surface side of the secondsupport substrate 210. In a mode where the liquid crystal display device1 include two pairs of light sources (first light source 31X and secondlight source 31Y, as well as first back surface side light source 32Xand second back surface side light source 32Y) as shown in FIG. 10C, theanisotropic light diffusion film 14 may be disposed on the back surfaceside of the first support substrate 110. In a mode where the liquidcrystal display device 1 includes two pairs of light sources (firstlight source 31X and second light source 31Y, as well as first backsurface side light source 32X and second back surface side light source32Y) as shown in FIG. 10D, the anisotropic light diffusion film 14 maybe disposed on the viewing surface side of the second support substrate210.

The anisotropic light diffusion film 14 may have a function to diffuselight in both a right oblique view and a left oblique view of the mainsurface of the anisotropic light diffusion film 14, or may have afunction to diffuse light in either a right oblique view or a leftoblique view.

The anisotropic light diffusion film 14 may be, for example, the lightdiffusion film (a hybrid film with high and low refractive indices)disclosed in WO 2016/051560 or a PDLC sheet. With such an anisotropiclight diffusion film 14, the efficiency of light diffusion toward thefront increases. The PDLC sheet is a normal PDLC sheet that is in thescattering state with no voltage applied while it is in the transparentstate with voltage applied, and contributes to reduction in thickness ascompared with the case of using a glass base material. The PDLC sheetcan be, for example, a PDLC film available from SMARTINT, INC.

FIG. 11A is a schematic perspective view of an anisotropic lightdiffusion film in the liquid crystal display device of Modified Example3. FIG. 11B is a schematic cross-sectional view of the anisotropic lightdiffusion film in the liquid crystal display device of Modified Example3. An example of the anisotropic light diffusion film 14 is described inmore detail with reference to FIG. 11A and FIG. 11B. The anisotropiclight diffusion film 14 in FIG. 11A and FIG. 11B includes a firstinternal structure 4020 and a second internal structure 4030 which arecolumnar structures (4020 a, 4030 a). Yet, FIG. 11B is used as acomprehensive view encompassing the case where the first and secondinternal structures (4020, 4030) are columnar structures (4020 a, 4030a), and cases where, for example, the first and second internalstructures (4020, 4030) are any other internal structures such as louverstructures.

As shown in FIG. 11A and FIG. 11B, the anisotropic light diffusion film14 includes a single-layered light diffusion layer 4050 including,sequentially from the bottom in the film thickness direction, the firstcolumnar structure 4020 a and the second columnar structure 4030 a withcolumns (4012 a, 4012 a′) as regions having a relatively high refractiveindex (4012, 4012′) in a region 4011 having a relatively low refractiveindex.

The columns 4012 a in the first columnar structure 4020 a each have abent portion 4014 at the middle point in the film thickness direction.

FIG. 12 is another schematic perspective view of the anisotropic lightdiffusion film in the liquid crystal display device of Modified Example3. The light diffusion properties of the anisotropic light diffusionfilm 14 are described in more detail based on an example in which thefirst internal structure 4020 and the second internal structure 4030 areboth columnar structures (4020 a, 4030 a).

As shown in FIG. 12 , the anisotropic light diffusion film 14 includestherein the first columnar structure 4020 a and the second columnarstructure 4030 a, and the columns in the first columnar structure 4020 aeach have a bent portion 4014. Thus, as shown in FIG. 12 , the threelight-diffusing angle-of-incidence regions formed by the first columnarstructure 4020 a and the second columnar structure 4030 a are overlappedwhile they are shifted by an appropriate range, so that thelight-diffusing angle-of-incidence region as the whole film can beeffectively increased.

In the columnar structures, the incident light with an angle ofincidence substantially parallel to the inclination angle of the columnsconstituting the columnar structure can be efficiently diffused withoutloss. This is because such an angle of incidence is included in thelight-diffusing angle-of-incidence region. However, incident light withan angle of incidence that is completely the same as the inclinationangle of the columns may be transmitted without sufficient diffusion. Incontrast, the anisotropic light diffusion film 14 can effectively solvethis problem.

For example, as with the incident light indicated by the arrow A,incident light with an angle of incidence that is completely parallel tothe inclination angle of the columns in the second columnar structure4030 a tends not to be diffused sufficiently by the second columnarstructure 4030 a. However, the anisotropic light diffusion film 14 shownin FIG. 12 uses the first columnar structure 4020 a including columnseach with a bent portion 4014 to gradually diffuse light in two stages,and thus can ultimately diffuse light sufficiently.

Also, for example, as with the incident light indicated by the arrow B,incident light with an angle of incidence significantly different fromthe inclination angle of columns in the second columnar structure 4030 ais merely diffused in a crescent moon shape by the side surfaces of thecolumns in the second columnar structure 4030 a, so that the diffusionby the second columnar structure 4030 a tends to be insufficient.However, the anisotropic light diffusion film 14 shown in FIG. 12 usesthe first columnar structure 4020 a including columns each with a bentportion 4014, and thus can ultimately diffuse light sufficiently.

Thus, the anisotropic light diffusion film 14 can effectively increasethe light-diffusing angle-of-incidence region as the whole film whileeffectively reducing or preventing changes in light diffusion propertiescaused by changes in angle of incidence of incident light.

Although the case where light is incident on the second columnarstructure side has been described, light is diffused based on the samemechanism when light is incident on the first columnar structure side.Also, diffusion at three stages was described, but light may be diffusedat four or more stages.

FIG. 13A and FIG. 13B are other examples of a schematic cross-sectionalview of the anisotropic light diffusion film in the liquid crystaldisplay device of Modified Example 3. In FIG. 11A, FIG. 11B, and FIG. 12, the anisotropic light diffusion film 14 was described based on theexample in which the first and second internal structures are bothcolumnar structures, but the first and second internal structures arenot limited to this example. Specifically, possible modes include a modein which the first and second internal structures are louver structures(4020 b, 4030 b) as shown in FIG. 13A, a mode in which the firstinternal structure is the louver structure 4020 b and the secondinternal structure is the columnar structure 4030 a as shown in FIG.13B, and a mode in which the first internal structure is the columnarstructure 4020 a and the second internal structure is the louverstructure 4030 b.

The columnar structure isotropically diffuses incident light (diffuseslight such that the planar shape of the diffused light is substantiallycircular), while the louver structure anisotropically diffuses incidentlight (diffuses light such that the planar shape of the diffused lightis linear).

As shown in FIG. 10A and FIG. 10B, the second liquid crystal panel 12 ofthe present embodiment may include, sequentially from its back surfaceside toward its viewing surface side, the third support substrate 610,the liquid crystal layer 800, the fourth support substrate 910, and ananisotropic light reflection film 15 that has a function to transmitlight in a front view and reflect light in an oblique view. This modecan increase the recycling efficiency of light from the backlight 50 andfurther increase the luminance of the liquid crystal display device 1.

Examples of the anisotropic light reflection film 15 include dielectricmultilayer mirrors and luminance increasing films.

A dielectric multilayer mirror has a structure in which layers of adielectric material having a high refractive index and layers of adielectric material having a low refractive index are alternatelystacked on a substrate. Examples of the dielectric materials having ahigh refractive index include TiO₂. Examples of the dielectric materialshaving a low refractive index include SiO₂. The dielectric multilayermirror has a structure in which, for example, layers of a dielectricmaterial having a high refractive index and layers of a dielectricmaterial having a low refractive index are stacked alternately inseveral to several tens of layers. Non-limiting examples of thesubstrate include substrates transparent to light, such as glasssubstrates. Examples of the dielectric multilayer mirror includePICASUS® available from Toray Industries, Inc.

The luminance increasing film is an optical component that transmitslight polarized in a certain direction (light vibrating in the certaindirection) and reflects light polarized in the other directions.Examples of the luminance increasing film include DBEF® available from3M Company.

As shown in FIG. 10A and FIG. 10B, the liquid crystal display device 1may include a first mirror 61X on the viewing surface side of the secondliquid crystal panel 12 and near the first light source 31X, and asecond mirror 61Y on the viewing surface side of the second liquidcrystal panel 12 and near the second light source 31Y. This mode usesthe anisotropic light reflection film 15 to reflect light from the firstlight source 31X and light from the second light source 31Y toward theviewing surface side for recycling, and thus can increase the light useefficiency.

The first mirror 61X and the second mirror 61Y may each be any componenthaving a reflection function. The first mirror 61X and the second mirror61Y each have a width of, for example, 1 cm.

As shown in FIG. 10C and FIG. 10D, the liquid crystal display device 1may further include a third mirror 62X disposed on the viewing surfaceside of the first light source 31X, a fourth mirror 62Y disposed on theviewing surface side of the second light source 31Y, a fifth mirror 63Xdisposed on the back surface side of the first back surface side lightsource 32X, and a sixth mirror 63Y disposed on the back surface side ofthe second back surface side light source 32Y. This mode enables easiercollection of light from the first light source 31X, light from thesecond light source 31Y, light from the first back surface side lightsource 32X, and light from the second back surface side light source 32Yto the central portion of the first liquid crystal panel 11.

The third mirror 62X, the fourth mirror 62Y, the fifth mirror 63X, andthe sixth mirror 63Y may each be any component that has a reflectionfunction.

As shown in FIG. 10C and FIG. 10D, the liquid crystal display device 1may include a first anisotropic light reflection film 70X disposedbetween the third mirror 62X and the fifth mirror 63X to receive lightfrom the first light source 31X and light from the first back surfaceside light source 32X, and a second anisotropic light reflection film70Y disposed between the fourth mirror 62Y and the sixth mirror 63Y toreceive light from the second light source 31Y and light from the secondback surface side light source 32Y. This mode can make an LED bulb lessobservable from the viewing surface side when at least one of the firstlight source 31X, the second light source 31Y, the first back surfaceside light source 32X, or the second back surface side light source 32Yincludes an LED.

Examples of the first anisotropic light reflection film 70X and thesecond anisotropic light reflection film 70Y include luminanceincreasing films. Examples of the luminance increasing films includethose mentioned above.

EXAMPLES

Hereinafter, the present invention is described in more detail based onexamples and comparative example. The present invention is not limitedto these examples.

Example 1-1

The liquid crystal display device of Embodiment 1 shown in FIG. 1 wasproduced as a liquid crystal display device of Example 1-1.

First, the first liquid crystal panel 11 in the liquid crystal displaydevice of Example 1-1 is described. The first substrate 100 includingthe pixel electrodes 120 formed from ITO and the second substrate 200including the common electrode 220 formed from ITO were prepared. Thesurfaces of the pixel electrodes 120 remote from the first supportsubstrate 110 and the surface of the common electrode 220 remote fromthe second support substrate 210 each were coated with an alignment filmmaterial containing a polymer capable of undergoing photoisomerization,and then subjected to photoalignment treatment such that the firstalignment film 410 and the second alignment film 420 were formed. Thephotoalignment treatment for the first alignment film 410 and the secondalignment film 420 was performed such that they would provideantiparallel alignment.

The first substrate 100 and the second substrate 200 were then disposedsuch that the first alignment film 410 and the second alignment film 420faced each other. Between the first substrate 100 and the secondsubstrate 200 was injected a composition (polymer dispersed liquidcrystal material) containing 90.6 wt % host liquid crystal (liquidcrystal components 320), i.e., positive liquid crystal; 8.96 wt %photopolymerizable liquid crystal compound (monomer); and 0.448 wt %polymerization initiator. The liquid crystal components 320 were aliquid crystal compound having a Δn of 0.18, a Δε of +20, and arotational viscosity γ1 of 206 mPa·s. The photopolymerizable liquidcrystal compound was a monomer containing a mesogen group, aphotoreactive group, and an acrylate group. The polymerization initiatorwas OXE03 (available from BASF SE).

The polymer dispersed liquid crystal material was irradiated withultraviolet (UV) light with a light irradiation intensity of 50 mW/cm²,a light irradiation dose of 2 J/cm², and a dominant wavelength of 365 nm(i.e., 40-second irradiation) to polymerize the monomer, so that thepolymer dispersed liquid crystal 300 was formed between the firstsubstrate 100 and the second substrate 200. Thus, the first liquidcrystal panel 11 having a cell thickness of 3 μm was produced. The firstliquid crystal panel 11 did not include a black matrix layer or a colorfilter layer.

The second liquid crystal panel 12 in the liquid crystal display device1 of Example 1-1 was an existing VA mode liquid crystal panel in whichpolarizing plates were disposed in crossed Nicols. As in the existingtechnique, the backlight 50 including a light guide plate and an LEDlight source on an edge surface of the light guide plate was disposed onthe back surface side of the second liquid crystal panel 12.

The first light source 31X and the second light source 31Y each were arod-like light source in which the red LEDs 31R were arranged in astraight line, the green LEDs 31G were arranged in a straight line, andthe blue LEDs 31B were arranged in a straight line. The first lightsource 31X and the second light source 31Y were driven based on the FSCsystem for color display.

In Example 1-1, the length and angle of each portion in FIG. 1 were setas follows.h11=h12=8 cma=20 cmb=10 cmθ11=θ12=68°

The first liquid crystal panel 11 in the liquid crystal display deviceof Example 1-1 produced as described above was a reverse mode liquidcrystal panel that operated in the transparent state with no voltageapplied and shifted into the scattering state with voltage applied. Alsoin Example 1-1, substitution resulted in 1≤8≤{20/tan 68°}≈8.08, meaningthat the liquid crystal display device satisfied the (formula 1-1) and(formula 1-2).

Example 1-2

FIG. 14 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-2. FIG. 15A is a graph of angle dependence of thetransmittance of a light-shielding louver sheet in the liquid crystaldisplay device of Example 1-2. FIG. 15B is an enlarged view of a regionsurrounded by the rectangle in the graph of FIG. 15A. FIG. 15C is aschematic view showing a method of determining the angle dependence ofthe transmittance of the light-shielding louver sheet in the liquidcrystal display device of Example 1-2.

The liquid crystal display device of Example 1-2 as shown in FIG. 14 wasproduced as in Example 1-1, except that a light-shielding louver sheetavailable from Shin-Etsu Polymer Co., Ltd. having the angle dependenceof transmittance shown in FIG. 15A and FIG. 15B was disposed as thelight-shielding louver 13 on the viewing surface side of the firstliquid crystal panel 11. The light-shielding louver sheet included thelight-shielding layers 1311 at a pitch P of 0.100 mm, a viewing angle of48°, and a maximum light transmittance angle of 0°. The pairedtransparent films 132 each were a 0.2-mm-thick PC film. Thelight-shielding louver sheet had a thickness of 0.79 mm.

Herein, the angle dependence of the transmittance of the light-shieldinglouver (for example, the light-shielding louver sheet) was determined bythe method shown in FIG. 15C with the panel/module evaluation systemLCD-5200 (available from Otsuka Electronics Co., Ltd.). Specifically,the panel/module evaluation system LCD-5200 was used to measure theluminance at each angle θ when the light-shielding louver was disposedas shown in FIG. 15C, and the luminance at an angle θ of 0° when nolight-shielding louver was disposed. The luminance at each angle θ whenthe light-shielding louver was disposed was divided by the luminance atan angle θ of 0° when no light-shielding louver was disposed todetermine the transmittance at each angle θ. The light source used tomeasure the luminance was a halogen lamp. The measurement wavelength wasset to about 550 nm, and the acceptance angle was about 2°. Thelight-shielding louver sheet used in Example 1-2 had a transmittance oflower than 1% at an angle θ of 23.5°, exhibiting a high light-shieldingcapability.

Example 1-3

FIG. 16 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-3. FIG. 17 is a schematic view showing a method ofdetermining the angle dependence of the transmittance of an opticalfilm. The liquid crystal display device 1 of Example 1-3 shown in FIG.16 was produced as in Example 1-1, except that the first liquid crystalpanel 11 included the anisotropic light diffusion film 14 on the backsurface side of the first support substrate 110.

In Example 1-3, the anisotropic light diffusion film 14 was ananisotropic light diffusion film 1-a having the optical characteristicsshown in the following Table 1. The following Table 1 shows the angledependence of the transmittance of the anisotropic light diffusion film1-a.

Herein, the angle dependence of the transmittance of an optical filmsuch as an anisotropic light diffusion film or an anisotropic lightreflection film was determined by the method shown in FIG. 17 with thepanel/module evaluation system LCD-5200 (available from OtsukaElectronics Co., Ltd.). Specifically, the panel/module evaluation systemLCD-5200 was used to measure the luminance at each angle θi (=θd) whenthe optical film was disposed as shown in FIG. 17 . The luminance ateach angle θi (=θd) was divided by the luminance at θi=θd=0° todetermine the transmittance at each angle θi (=θd). In other words, thetransmittance at each angle was calculated, with the transmittance at anangle of 0° taken as 100%. The light source used to measure theluminance was a halogen lamp. The measurement wavelength was set toabout 550 nm and the acceptance angle was about 2°. FIG. 17 shows thecase where the optical film is the anisotropic light diffusion film orthe anisotropic light reflection film.

TABLE 1 Angle Transmittance 0° 100% ±15°  95% ±30° 31 to 36% ±40° 3.1 to3.3% ±45° 3.1 to 3.5% ±50° 2.9 to 3.3% ±60° 1.3 to 1.4%

Example 1-4

FIG. 18 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-4. The liquid crystal display device 1 of Example1-4 shown in FIG. 18 was produced as in Example 1-1, except that thesecond liquid crystal panel 12 included the anisotropic light reflectionfilm 15 on the viewing surface side of the fourth support substrate 910,the first mirror 61X and the second mirror 61Y were disposed at therespective ends of the anisotropic light reflection film 15, light fromthe first light source 31X and light from the second light source 31Ywere emitted toward the back surface side, and θ11=θ12=75°.

In Example 1-4, the anisotropic light reflection film 15 was theanisotropic light reflection film having the optical characteristicsshown in the following Table 2. The following Table 2 shows the angledependence of transmittance of the anisotropic light reflection film.

TABLE 2 Angle Transmittance  0° 100% ±15°  98 to 99% ±30°  93 to 94%±40°  87 to 88% ±45°  82 to 83% ±50°  76 to 77% ±60°  63 to 64%

In Example 1-4, substitution resulted in 1≤4≤{20/tan 75°}≈5.36, meaningthat the liquid crystal display device satisfied (formula 1-1) and(formula 1-2).

Example 1-5

FIG. 19 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 1-5. The liquid crystal display device 1 of Example1-5 shown in FIG. 19 was produced as in Example 1-1, except that thefirst liquid crystal panel 11 included the anisotropic light diffusionfilm 14 on the back surface side of the first support substrate 110 andthe second liquid crystal panel 12 included the anisotropic lightreflection film 15 on the viewing surface side of the fourth supportsubstrate 910, the first mirror 61X and the second mirror 61Y at therespective ends of the anisotropic light reflection film 15, light fromthe first light source 31X and light from the second light source 31Ywere emitted toward the back surface side, h11=h12=4 cm, b=5 cm, andθ11=θ12=75°.

In Example 1-5, the anisotropic light diffusion film 14 was theanisotropic light diffusion film 1-a, and the anisotropic lightreflection film 15 was the anisotropic light reflection film having theoptical characteristics shown in Table 2.

In Example 1-5, substitution resulted in 1≤4≤{20/tan 75°}≈5.36 cm,meaning that the liquid crystal display device satisfied (formula 1-1)and (formula 1-2).

Example 1-6

The liquid crystal display device 1 of Example 1-6 was produced as inExample 1-5, except that h11=h12=8 cm, b=10 cm, and θ11=θ12=68°.

In Example 1-6, substitution resulted in 1≤8≤{20/tan 68°}≈8.08, meaningthat the liquid crystal display device satisfied (formula 1-1) and(formula 1-2).

Example 2-1

FIG. 20 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 2-1. The liquid crystal display device 1 of Example2-1 shown in FIG. 20 had the same structure as that of Example 1-1,except that the first back surface side light source 32X and the secondback surface side light source 32Y were used. The angles wereθ21=θ22=57°.

In Example 2-1, substitution resulted in 1≤8≤{20/tan 68°}≈8.08 cm,meaning that the liquid crystal display device satisfied (formula 1-1)and (formula 1-2), and θ11−θ21=θ12−θ22=68°−57°=11°>10°, meaning that theliquid crystal display device satisfied (formula 2-1) and (formula 2-2).

Example 2-2

FIG. 21 is a schematic cross-sectional view of a liquid crystal displaydevice of Example 2-2. The liquid crystal display device of Example 2-2shown in FIG. 21 was produced as in Example 2-1, except that thelight-shielding louver 13 same as the one used in Example 1-2 wasdisposed on the viewing surface side of the first liquid crystal panel11.

Example 2-3

The liquid crystal display device 1 of Example 2-3 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the back surface side of thefirst support substrate 110 as shown in FIG. 10C. In Example 2-3, theanisotropic light diffusion film 14 was the anisotropic light diffusionfilm 1-a.

Example 2-4

The liquid crystal display device 1 of Example 2-4 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the viewing surface side of thesecond support substrate 210 as shown in FIG. 10D. In Example 2-4, theanisotropic light diffusion film 14 was the anisotropic light diffusionfilm 1-a.

Example 2-5

The liquid crystal display device 1 of Example 2-5 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the back surface side of thefirst support substrate 110 as shown in FIG. 10C. In Example 2-5, theanisotropic light diffusion film 14 was an anisotropic light diffusionfilm 1-b having the optical characteristics shown in the following Table3. The following Table 3 shows the angle dependence of the transmittanceof the anisotropic light diffusion film 1-b.

TABLE 3 Angle Transmittance  0°  100% ±15° 97 to 98% ±30° 72 to 89% ±40° 8 to 13% ±45° 3.1 to 3.6%  ±50°  3.4% ±60° 1.7 to 2.2% 

Example 2-6

The liquid crystal display device 1 of Example 2-6 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the viewing surface side of thesecond support substrate 210 as shown in FIG. 10D. In Example 2-6, theanisotropic light diffusion film 14 was the anisotropic light diffusionfilm 1-b.

Example 2-7

As shown in FIG. 10C, the liquid crystal display device 1 of Example 2-7was produced as in Example 2-1, except that in the first liquid crystalpanel 11, the anisotropic light diffusion film 14 was disposed on theback surface side of the first support substrate 110. In Example 2-7,the anisotropic light diffusion film 14 was the anisotropic lightdiffusion film 1-c having the optical characteristics shown in thefollowing Table 4. The following Table 4 shows the angle dependence oftransmittance of the anisotropic light diffusion film 1-c.

TABLE 4 Angle Transmittance −60°  1.7% −50°  3.0% −45°  4.2% −40°  3.7%−30°   21% −15°   92%  0°  100% +15°  100% +30°   98% +40°   95% +45°  93% +50°   90% +60°   81%

Example 2-8

The liquid crystal display device 1 of Example 2-8 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the viewing surface side of thesecond support substrate 210 as shown in FIG. 10D. In Example 2-8, theanisotropic light diffusion film 14 was the anisotropic light diffusionfilm 1-c.

Example 2-9

The liquid crystal display device 1 of Example 2-9 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the back surface side of thefirst support substrate 110 as shown in FIG. 10C. In Example 2-9, theanisotropic light diffusion film 14 was an anisotropic light diffusionfilm 1-d having the optical characteristics shown in the following Table5. The following Table 5 shows the angle dependence of the transmittanceof the anisotropic light diffusion film 1-d.

TABLE 5 Angle Transmittance −60° 2.3%  −50° 3.5%  −45° 3.7%  −40° 13%−30° 79% −15° 98%    0° 100%  +15° 100%  +30° 98% +40° 95% +45° 93% +50°90% +60° 81%

Example 2-10

The liquid crystal display device 1 of Example 2-10 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the viewing surface side of thesecond support substrate 210 as shown in FIG. 10D. In Example 2-10, theanisotropic light diffusion film 14 was the anisotropic light diffusionfilm 1-d.

Example 2-11

The liquid crystal display device 1 of Example 2-11 was produced as inExample 2-1, except that the second liquid crystal panel 12 included theanisotropic light reflection film 15 on the viewing surface side of thefourth support substrate 910. In Example 2-11, the anisotropic lightreflection film 15 was the anisotropic light reflection film having theoptical characteristics shown in Table 2.

Example 2-12

The liquid crystal display device 1 of Example 2-12 was produced as inExample 2-1, except that the first liquid crystal panel 11 included theanisotropic light diffusion film 14 on the back surface side of thefirst support substrate 110 and the second liquid crystal panel 12included the anisotropic light reflection film 15 on the viewing surfaceside of the fourth support substrate 910.

In Example 2-12, the anisotropic light diffusion film 14 was theanisotropic light diffusion film 1-a, and the anisotropic lightreflection film 15 was the anisotropic light reflection film having theoptical characteristics shown in Table 2.

Comparative Example 1

FIG. 22 is a schematic cross-sectional view of a liquid crystal displaydevice of Comparative Example 1. A liquid crystal display device 1RF ofComparative Example 1 was produced by disposing a backlight 50R on theback surface side of the first liquid crystal panel 11 produced as inExample 1-1 with an adhesive component 80 such as OCA. The backlight 50Rincluded the LED light source 51R on the edge surface of the light guideplate 52R.

(Evaluation of Examples and Comparative Example)

The transmittance in the transparent state, the front luminance of thepanel central portion in the scattering state, the front contrast ratioof the panel central portion, and how the LED bulbs were observed in anoblique view were evaluated in each of the examples and the comparativeexample. The following Table 6 shows the results.

The evaluations were performed as follows.

<Transmittance in Transparent State>

The luminance was measured with the spectroradiometer (SR-UL1) availablefrom Topcon Technohouse Corporation when the 19-inch first liquidcrystal panel of each of the examples and comparative example with novoltage applied was placed on a common backlight (light source forliquid crystal display devices) and when nothing was placed on thebacklight. The luminance measured when the first liquid crystal panelwith no voltage applied was placed on the backlight was divided by theluminance measured when nothing was placed on the backlight, so that thetransmittance in the transparent state was determined. In the luminancemeasurement, the light source was a halogen lamp, the acceptance anglewas 2°, and the measurement wavelength was about 550 nm.

<Front Luminance of Panel Central Portion in Scattering State and FrontContrast Ratio of Panel Central Portion>

The 19-inch first liquid crystal panel of each of the examples andcomparative example was placed on a common backlight (light source forliquid crystal display devices), and the distance between the firstliquid crystal panel and the spectroradiometer available from TopconTechnohouse Corporation was set to about 50 cm, so that the luminance(white luminance) in the scattering state and the luminance in thetransparent state were measured in a dark room. The luminance in thescattering state was taken as the front luminance of the panel centralportion in the scattering state. The luminance in the scattering statewas divided by the luminance in the transparent state to determine thefront contrast ratio of the panel central portion. In luminancemeasurement, the light source was a halogen lamp, the acceptance anglewas 2°, and the measurement wavelength was about 550 nm.

<LED Bulb Appearance in Oblique View>

The appearance was determined by subjective evaluation of whether or notbright lines of the red LEDs 31R, the green LEDs 31G, and the blue LEDs31B were visually observed.

TABLE 6 Structure Anisotropic Anisotropic Effect Light source Light-light light Example/ Transmittance irradiation shielding diffusionreflection Comparative in transparent system Light source louver filmfilm Example state Oblique light First light source — — — Example 1-1 A(65%) incidence and second light source Included — — Example 1-2 B (50%)system (one pair, two rod-like — Included — Example 1-3 A (60%) lightsources in total) — — Included Example 1-4 A (65%) — Included IncludedExample 1-5 A (60%) — Included Included Example 1-6 A (60%) First lightsource — — — Example 2-1 A (65%) and second light source Included — —Example 2-2 B (50%) and third light source — Included — Example 2-3 A(60%) and fourth light source — Included — Example 2-4 A (60%) (twopairs, four rod-like — Included — Example 2-5 A (60%) light sources intotal) — Included — Example 2-6 A (60%) — Included — Example 2-7 A (60%)— Included — Example 2-8 A (60%) — Included — Example 2-9 A (60%) —Included — Example 2-10 A (60%) — — Included Example 2-11 A (65%) —Included Included Example 2-12 A (60%) Light guide Rod-like light source— — — Comparative A (65%) system on each edge surface Example 1 of lightguide plate (one pair, two rod- like light sources in total) EffectDistance between first liquid crystal panel Front luminance Frontcontrast and first and Light source of panel central ratio of secondlight irradiation portion in panel central sources (h11 LED bulb insystem scattering state portion and h12) oblique view Oblique light C(102 cd/m²) A (5)  B (8 cm) C (Too bright, but  incidence depends onuse) system C (79 cd/m²)  A (4.3) B (8 cm)   A (Almost unobservable) A(138 cd/m²) A (4.6) B (8 cm) B (Blurring reduced brightness) B (113cd/m²) A (4.3) B (8 cm) C (Too bright, but  depends on use) A (153cd/m²) B (3.6) A (4 cm) B (Blurring reduced brightness) A (169 cd/m²) A(4.1) B (8 cm) B (Blurring reduced brightness) A (203 cd/m²) A (5.2) B(8 cm) C (Too bright)    A (158 cd/m²) A (4.5) B (8 cm)   A (Almostunobservable) A (298 cd/m²) C (2.6) B (8 cm) B (Blurring reducedbrightness) A (240 cd/m²) C (2.3) B (8 cm) B (Blurring reducedbrightness) A (250 cd/m²) C (2.4) B (8 cm) B (Blurring reducedbrightness) A (246 cd/m²) C (2.4) B (8 cm) B (Blurring reducedbrightness) A (240 cd/m²) C (2.6) B (8 cm) B (Blurring reducedbrightness) A (212 cd/m²) C (2.6) B (8 cm) B (Blurring reducedbrightness) A (202 cd/m²) C (2.5) B (8 cm) B (Blurring reducedbrightness) A (206 cd/m²) C (2.5) B (8 cm) B (Blurring reducedbrightness) A (225 cd/m²) A (4.5) B (8 cm) C (Too bright, but  dependson use) A (337 cd/m²) A (4.3) B (8 cm) B (Blurring reduced brightness)Light guide D (60 cd/m²)  D (1.4) A (0 cm)   A (Almost unobservable)system

In Table 6, the subjective evaluation was performed based on thefollowing criteria.

-   -   A: Excellent    -   B: Good    -   C: Average    -   D: Poor

In evaluation of LED bulbs in an oblique view in Table 6, it isimportant that the LED light is not observed by the viewer.

Also, the NTSC ratio in the liquid crystal display device of each ofExample 2-3, Examples 2-7 to 2-10, and Comparative Example 1 wasdetermined. The NTSC ratio was 5.7% in Example 2-3, 2.8% in Example 2-7,2.8% in Example 2-8, 2.5% in Example 2-9, 2.6% in Example 2-10, and20.5% in Comparative Example 1. The NTSC ratio was determined asfollows. The chromaticity (x, y) of each of RGB in the first liquidcrystal panel of each of the examples and comparative example wasmeasured with the spectroradiometer (SR-UL1) available from TopconTechnohouse Corporation to calculate the color gamut coverage (area).Thus, the ratio of the color gamut coverage to the area of NTSC (colorgamut standard) was determined.

The liquid crystal display devices of Examples 1-1 to 1-6 and 2-1 to2-12 can display images without a polarizing plate since its firstliquid crystal panel includes a polymer dispersed liquid crystal, thusreducing a decrease in transmittance in the transparent state. Also, inExamples 1-1 to 1-6 and 2-1 to 2-12, the back surface side main surface11P of the first liquid crystal panel 11 was irradiated with light froman oblique direction, so that the front luminance of the panel centralportion and the front contrast ratio of the panel central portion in thescattering state were successfully increased. In contrast, inComparative Example 1, light from the LED light source 51R was incidenton the edge surface of the light guide plate 52R, so that the frontluminance of the panel central portion and the front contrast ratio ofthe panel central portion in the scattering state were not increased.

The liquid crystal display devices of Examples 1-1 to 1-6 satisfying(formula 1-1) and (formula 1-2) increased the intensity of the frontscattering components in the scattering state and enabled furtherreduction of a decrease in luminance of the panel central portion in thescattering state, thus enabling even brighter display.

The liquid crystal display devices of Examples 2-1 and 2-2 satisfying(formula 1-1), (formula 1-2), (formula 2-1), and (formula 2-2) increasedthe intensity of the front scattering components in the scattering stateand enabled further reduction of a decrease in luminance of the panelcentral portion in the scattering state, thus enabling even brighterdisplay.

The liquid crystal display device 1RF of Comparative Example 1 had afront luminance of the panel central portion in the scattering state of60 cd/m² and a front contrast ratio of the panel central portion of 1.4,and exhibited poor display quality in a front view, which was at a levelthat made the viewer uncomfortable.

FIG. 23 is a schematic view showing the evaluation of LED bulbs. In aliquid crystal display device including the light-shielding louver 13 aswith the liquid crystal display devices of Example 1-2 and Example 2-2,the LED bulbs were not observed even when the display device wasobserved at the observation position 2 or 3 from an oblilue direction asshown in FIG. 23 .

REFERENCE SIGNS LIST

-   -   1, 1RF: liquid crystal display device    -   1B, 1G, 1R: input grayscale data    -   1 b, 1 g, 1 r: applied grayscale data    -   4: pixel forming portion    -   11: first liquid crystal panel    -   11A: display portion    -   11P: back surface side main surface    -   11X: one edge portion    -   11Y: other edge portion    -   12: second liquid crystal panel    -   13: light-shielding louver    -   14: anisotropic light diffusion film    -   15: anisotropic light reflection film    -   20: transparent resin plate    -   31X: first light source    -   31Y: second light source    -   32X: first back surface side light source    -   32Y: second back surface side light source    -   31B, 31G, 31R: LED (light emitting diode)    -   40: TFT (thin film transistor)    -   42: liquid crystal capacitance    -   43: auxiliary capacitance    -   45: auxiliary capacitance electrode    -   46: pixel capacitance    -   50, 50R: backlight    -   51R: LED light source    -   52R: light guide plate    -   61X: first mirror    -   61Y: second mirror    -   62X: third mirror    -   62Y: fourth mirror    -   63X: fifth mirror    -   63Y: sixth mirror    -   70X: first luminance increasing film    -   70Y: second luminance increasing film    -   80: adhesive component    -   100: first substrate    -   110: first support substrate    -   120, 620: pixel electrode    -   131: louver layer    -   132: transparent film    -   200: second substrate    -   210: second support substrate    -   220, 930: common electrode    -   300: polymer dispersed liquid crystal    -   310: polymer network    -   320: liquid crystal component    -   410: first alignment film    -   420: second alignment film    -   510: first polarizing plate    -   520: second polarizing plate    -   600: third substrate    -   610: third support substrate    -   710: third alignment film    -   720: fourth alignment film    -   800: liquid crystal layer    -   900: fourth substrate    -   910: fourth support substrate    -   920: color filter layer    -   1000: preprocessing unit    -   1100: signal separation circuit    -   1200: data correction circuit    -   1300(R): red field memory    -   1300(G) green field memory    -   1300(B): blue field memory    -   1311: light-shielding layer    -   1312: transparent layer    -   2000: timing controller    -   3100: gate driver    -   3200: source driver    -   3300: LED driver    -   4011: region having relatively low refractive index    -   4012, 4012′: region having relatively high refractive index    -   4012 a, 4012 a′: column    -   4014: bent portion    -   4020: first internal structure    -   4020 a, 4030 a: columnar structure    -   4020 b, 4030 b: louver structure    -   4030: second internal structure    -   4050: light diffusion layer    -   DIN: input image signal    -   DV: digital video signal    -   GCK: gate clock signal    -   GSP: gate start pulse signal    -   GL, GL1 to GLm: gate line    -   LS: latch strobe signal    -   S1: LED driver control signal    -   S2: light source control signal    -   SCK: source clock signal    -   SL, SL1 to SLn: source line    -   SSP: source start pulse signal

What is claimed is:
 1. A liquid crystal display device comprising,sequentially from its viewing surface side toward its back surface side:a first liquid crystal panel; a light source; a back surface side lightsource; and a second liquid crystal panel, the first liquid crystalpanel including a polymer dispersed liquid crystal containing a polymernetwork and liquid crystal components, the light source being configuredto directly irradiate a back surface side main surface of the firstliquid crystal panel with light from an oblique direction withoutguiding light emitted from the light source through any other elementbetween the light source and the first liquid crystal panel, and theback surface side light source irradiating the back surface side mainsurface of the first liquid crystal panel with light from an obliquedirection without guiding light emitted from the back surface side lightsource through any other element between the back surface side lightsource and the first liquid crystal panel.
 2. The liquid crystal displaydevice according to claim 1, wherein the first liquid crystal paneldisplays an image based on a field-sequential color system, and thelight source includes light-emitting elements configured to emit lightrays of colors different from one another.
 3. The liquid crystal displaydevice according to claim 1, wherein the first liquid crystal panelfurther includes a thin film transistor.
 4. The liquid crystal displaydevice according to claim 1, wherein a distance between the first liquidcrystal panel and the second liquid crystal panel is a [cm] or shorter,where a is calculated from a length 2 a [cm] of a long side of the firstliquid crystal panel.
 5. The liquid crystal display device according toclaim 1, wherein the liquid crystal display device satisfies thefollowing (formula 1-1):1 cm≤h11≤{a/(tan θ11)}  (formula 1-1) where a is calculated from alength 2 a [cm] of a long side of the first liquid crystal panel, h11[cm] is a distance between the first liquid crystal panel and the lightsource, and θ11[° ] is an angle of incidence of light from the lightsource on the back surface side main surface of the first liquid crystalpanel.
 6. The liquid crystal display device according to claim 1,wherein the light source is a first light source and disposedcorrespondingly to one of a pair of edge portions of the first liquidcrystal panel facing each other, the liquid crystal display devicefurther includes a second light source that is disposed between thefirst liquid crystal panel and the second liquid crystal panel andcorrespondingly to the other of the edge portions, the second lightsource is configured to irradiate the back surface side main surface ofthe first liquid crystal panel with light from an oblique direction, andan angle of incidence of light from the first light source on the backsurface side main surface of the first liquid crystal panel is the sameas an angle of incidence of light from the second light source on theback surface side main surface of the first liquid crystal panel.
 7. Theliquid crystal display device according to claim 1, wherein the liquidcrystal display device satisfies the following (formula 1-1) and(formula 2-1):1 cm≤h11≤{a/(tan θ11)}  (formula 1-1)θ11−θ21>10°  (formula 2-1) where a is calculated from a length 2 a [cm]of a long side of the first liquid crystal panel, h11 [cm] is a distancebetween the first liquid crystal panel and the light source, θ11[° ] isan angle of incidence of light from the light source on the back surfaceside main surface of the first liquid crystal panel, and θ21[° ] is anangle of incidence of light from the back surface side light source onthe back surface side main surface of the first liquid crystal panel. 8.The liquid crystal display device according to claim 1, wherein the backsurface side light source is a first back surface side light source anddisposed correspondingly to one of a pair of edge portions of the firstliquid crystal panel facing each other, the liquid crystal displaydevice further includes a second back surface side light source that isdisposed between the light source and the second liquid crystal paneland correspondingly to the other of the edge portions, the second backsurface side light source is configured to irradiate the back surfaceside main surface of the first liquid crystal panel with light from anoblique direction, and an angle of incidence of light from the firstback surface side light source on the back surface side main surface ofthe first liquid crystal panel is the same as an angle of incidence oflight from the second back surface side light source on the back surfaceside main surface of the first liquid crystal panel.
 9. The liquidcrystal display device according to claim 1, wherein the first liquidcrystal panel further includes a first support substrate on a backsurface side of the polymer dispersed liquid crystal, and a secondsupport substrate on a viewing surface side of the polymer dispersedliquid crystal.
 10. The liquid crystal display device according to claim9, wherein the first liquid crystal panel further includes an alignmentfilm at least one of between the first support substrate and the polymerdispersed liquid crystal or between the second support substrate and thepolymer dispersed liquid crystal, and the alignment film is a horizontalalignment film configured to align the liquid crystal components in adirection parallel to a surface of the alignment film.
 11. The liquidcrystal display device according to claim 10, wherein the liquid crystalcomponents have a positive anisotropy of dielectric constant.
 12. Theliquid crystal display device according to claim 9, wherein the firstliquid crystal panel further includes a transparent resin plate on aback surface side of the first support substrate.
 13. The liquid crystaldisplay device according to claim 9, wherein the first liquid crystalpanel further includes an anisotropic light diffusion film having afunction to transmit light in a front view and scatter light in anoblique view on at least one of a back surface side of the first supportsubstrate or a viewing surface side of the second support substrate. 14.The liquid crystal display device according to claim 1, wherein thesecond liquid crystal panel includes, sequentially from its back surfaceside toward its viewing surface side, a third support substrate, aliquid crystal layer, and a fourth support substrate.